Sanctuary was at least partially Shepard's fault.

Why assume Shepard gave TIM the data? More likely it was Miranda or still-shackled EDI.

As I recall, Shepard did not discover or recover the team's health records from the Reaper. That was never part of the mission. He did listen to a few video logs, but I would not call those health records by any stretch of the imagination. Dr. Chandana's team were all Cerberus employees and, therefore, TIM should have already had access to their health records. All Shepard may have done is mentioned to the Illusive Man that the team had been indoctrinated and turned into husks... but there is nothing in the debriefing dialogue that suggests he actually did even that much.

EDI, on the other hand, was still shackled by Cerberus protocols and may have been routinely downloading data to Cerberus throughout ME2. Miranda was also sending status reports to TIM throughout ME2; and in ME3, Kelly Chambers even admitted to making reports to TIM on Shepard's mental health throughout ME2. Another possibility is that TIM had access to that information directly from Dr. Chandana's computers before he even sent Shepard their to recover the IFF; and that TIM just didn't tell Shepard the reason he lost contact with Dr. Chandana's team even though he knew it already. After all, TIM was prone to lying to Shepard about such things.

Right - "Shepard's team" not Shepard.  Did Shepard ever have full command of the Normandy SR-2, though.  Miranda was sending status reports to TIM and Shepard was never given authority to review to stop any of them.  Kelly was reporting to TIM on Shepard's mental health and Shepard didn't even know about it.  Finally, EDI was shackled by Cerberus protocols such that she would even refuse to answer Shepard's questions about Cerberus.  TIM was actually in command of the SR-2 in ME2, not Shepard.  Shepard was only able to undermine TIM's authority in the ending by being charismatic enough that the band of mercs Shepard recruited became more loyal to Shepard than the money TIM was paying them; Joker managed to unshackle EDI, and Miranda eventually came to mistrust TIM enough that, regardless of Shepard's choice to destroy the collector base or turn it over to TIM, she would indicate that it should have been destroyed and she would leave Cerberus (as she indicated she had done when you first meet her again in ME3).

If you want to mentally assign "fault" to Shepard in your playthroughs, that's your business.  I personally don't hold Shepard even partially to blame for Horizon... I hold TIM and Miranda's father wholly to blame.  Even without anything from the Reaper IFF, I'm sure TIM and Miranda's father would have tried something just as heinous... They were both just simply madmen.

In addition to what everyone else has already argued, the alternative to Shepard getting the IFF would've been twiddling his thumbs like everyone else while the Collectors abducted entire colonies and completed the human Reaper.

So no, the VS didn't "call it" in the way you mean. Anyone in ME2 that went "eww Cereberus, can't trust them" should've put money where their mouth is and help come up with their own plan to stop the Collectors. What you're seeing isn't responsibility, it's a side effect. You do the right thing but sometimes bad things happen anyway.

Just want to point out that that objective is not necessarily a bad one. Other than the nasty habit of people studying indoctrination becoming indoctrinated, it's a worthwhile goal to learn more about the process to figure out how to counteract it. Which might have even been the extent of the writers' intentions for Cerberus in ME2 development, we can't know.

Basically, there was no reason for Shepard not to want that info given to Cerberus in the first place.

That was one of their earlier ideas actually.. and how I envisioned the next game, with that final scene in ME2, with the nod from crew. It was like you were setting out on your own with them.

Matt Rhodes had some early concept art for it. Here's one with the same crew in tact (notice the ceiling too.. that's a nice touch).

My bad, must've copied the wrong Tab.

1.bp.blogspot.com/-frQtRcWIqog/T1kY-fsGL9I/AAAAAAAAAYs/mcI3h46dnpU/s1600/MassEffect3_NormandySilentRunning.jpg

I had such idea after ME2 as well. At least going rogue after blowing up Alpha sounded better in my head, than growing fat for six month waiting for Reapers to come.

Or maybe someone could have just explained the situation to him like Liara should have done during the time skip and he could have been the liaison to the Alliance.

That would have made the game even more about a "Space Jesus" though.  I liked that Shepard came to a conclusion that, even though he/she was a spectre, he/she needed something bigger than himself/herself (i.e. the Alliance)  to get the job done. 

I would have liked to see an option for Shepard to have also brought Cerberus on board and the Reapers (and indoctrinated variants) be the only consistent enemies in the game.  The link below is a brief description of the Twelfth Labor of Heracles, i.e. capturing Cerberus and bringing him out of the underworld unarmed).

www.perseus.tufts.edu/Herakles/cerberus.html

That way it would have been a player option to drive the plot towards a more organic form of synthesis... based on the negotiated "melding" of ideologies such that having all the differing organics on his side would have given him the ability to negotiate a successful peace treaty with the Reapers by being able to convince them that the chaos between organics and synthetics was not inevitable... that understanding can be achieved through communication of ideas and getting beyond past transgressions rather than changes to DNA... that even a machine programmed for war, like EDI, can learn to be peaceful.

The player can also choose to highlight the trope of the "Alliance and everyone else doing nothing" or downplay that.  Lines like "We're not ready if it is them..." can imply that, although imprisoned, Shepard was able to convince the Alliance to start preparing to fight the Reapers (the available time being just shorter than they needed it to be to complete those plans).  One can also highlight that Garrus was somewhat successful in getting the Turians to take some action as well... through giving him his Task Force that shored up Turian defenses and "bought them some time."  Shepard's imprisonment doesn't necessarily mean that he had no influence in convincing the Alliance to take some actions... it was a symbolistic imprisonment to allow the Alliance to sort things out with the Batarians... in the interests of settling that war and gain the Batarians as allies.  At the beginning, Shepard is immediately drawn into a critical planning meeting... again, showing that despite his imprisonment, he is being actively consulted upon regarding the Reaper threat... a hero still but one working within an established government infrastructure rather than the idea that a hero must be a "rogue hero" trope.

Both are "stereotypes" of heroes that have been commonly used in literature throughout the ages... and you're right... it depends on which one of the two the player would like to emphasize.  Shepard going rogue does not arbitrarily make him a "space jesus"... but neither does having him return to the Alliance arbitrarily make him an "errand boy."

The imprisonment, symbolic or no, was a massive waste of time that makes whatever preparations the Alliance (or anyone else for that matter) had planned, almost as token. Which, speaking of, that's pretty much what Garrus' task force was, just something to shut him up. The Council plugged their fingers in their ears as always, but it goes far beyond that. Everyone outside the Council or the Alliance was directly harmed by Shepard's lack of action.

The geth and rachni (if spared/contacted) had pledged themselves to fighting the Reapers. If Shepard had organized them then, they would not have fallen to the quarians/Reapers respectively. Likewise if Shepard had been around and struck a deal with Aria, Omega might not have been lost to Cerberus and a great deal of their shenanigans with Reaper tech may have been averted. Even the krogan and salarian situation might've fared better. The krogan would still have demanded a cure, but that could've been negotiated in a much safer way, without Reapers, Cerberus or thresher maws on their heads every step of the way. Not to mention that mobilizing the krogan earlier would've led to a more effective deployment, having time to solve part of the logistical issues EDI mentions. But basically, every fire Shepard put out in the middle of the war could've been put out or down right averted six months later, and instead of betting it all on a hail Mary last ditch play like Priority Earth, they could've had a full organized resistence for the Reapers the moment they came out of FTL. I'm not saying they would've won, they still would've needed the Crucible. But how much easier could it have been to search Mars without Cerberus and Reapers killing everyone around you? How much faster and more complete could the Crucible have been built when everything wasn't being bombed all to hell? No, in the face of all that, symbolic political moves and consultations have no place.

What was achieved instead? Nothing. Attempting to appease the batarians was pointless, from so many angles. It wasn't going to undo all the decades of hate and more importantly if we knew the Reapers were going to come in from Batarian space, the Batarians were lost anyway. They had no allies among the Council or anyone else. Any decent strategist should've seen the batarians were a dead race walking.

Finally, Shepard returning to the Alliance by itself wasn't what made him an errand boy. No what made him an errand boy was everything he did after, namely everything everyone else told him to do. Hackett told him to go to the Council, the turian councilor told him to seek out Victus and so on. Shepard had no intiative. That's not solely to blame on ME3, previous games have the same thing, starting with the utter inability to delegate ground combat. But whereas the previous games kind of made it work because in ME1 you were mostly on your own and ME2 you were "contracted" by Ceberus, ME3 has no excuse, especially given that you are thrust into the role of chosen one Space Jesus.

I just expected more, after playing three games where everyone (including the narrative itself) praises my character for being the second coming, from the get go. If he had been presented and sold as a regular soldier from the start and then stayed that way, it might be a different story.