Did Geth Heretics ever really exist?

When I first played the game, I assumed that they didn't know about the Reaper invasion until the Normandy arrived – if the information barrier between the Citadel space and the Veil works the same both ways, that was the case. Additionally, you receive some old news in-game about quarian pilgrims buying armament and being recalled to the fleet so they were committed to the action for a while already. Then I learned that there's a ton of ignorants who bash the Admiralty for launching the invasion after they learned about the Reapers and are unable to support this with any evidence. I tried to find any conclusive line in the script the day before yesterday but I found nothing.

Maybe because on some level they do feel, even if not in the same way as organics, and they don't want to leave their birth place because they are tied to it as much as the quarians are?

Methinks you are asking why don't the geth think or act like organics after specifically saying they aren't like organics. So why would their reasoning or logic make sense to us?

EDI says she experiences feedback which is akin to emotion but not the same thing.

Bioware does bad writing and retcons.  The result is that fans must make up their own theories to make sense of the plot or to make it fit better.

I think it is the result of having many different writers writing in isolation, contending with budget and design pressures, often having a limited understanding of the topic they want to write about, and many of them not even liking, understanding, or being well versed in science fiction. 

Possibly though I think the fact they didn't plan out even the vague outline of the trilogy from the start.

Honestly, the whole thing with the quarians not getting another planet of their own always sounded like a huge plot hole in the ME lore to me. It makes no sense.
I mean, you guys brought up Ekuna and make it sound like the Council doesn't let them settle anywhere, not even in the Terminus, where they should have no say whatsoever. But even if that was categorically true (and given how much of a pain in the ass the quarian flotilla seems to be for everyone, it also doesn't really sound politically feasible), it doesn't make sense that the quarians could not find some uncharted garden world somewhere in 300 years. The humans get to build something like 5 or 6 colonies on perfect garden worlds in the 8 years before they ever meet the Council races. They also go on to coloize half the attican traverse and plenty of planets in the Terminus in the next 30. The batarians, who are in somewhat of a cold war with the humans and on really bad relations with the council also get to settle multiple worlds in this region.
The quarians are only 17 million people. Just finding one single planet somewhere should be more than they ever need for the foreseeable future.
And as far as the restrictions in environmental conditions are concerned, well, Tali and a bunch of other say that in principle this is not really a problem, they'd just have to hang on to the suits for a couple of decades longer (which they already did now for several hundred years on their ships, so no biggie) and the fact that they even tried to settle Ekuna which has a whooping 4.1 earth gravities (which is why the Council decided to give it to the Elcor) kinda proves that they were not that choosy when it came right down to it.

My personal head canon explanation is therefore, that there probably was a large conservative political movement in the fleet, that opposed settling on another planet in order to keep pushing the agenda to get Rannoch back somehow. This party may have used arguments like "we can't live on another planet easily" or "the Council/pirates/whoever will never let us stay" but in principle the agenda was always to get back at the geth and thus keep the quarians from just settling on another planet somewhere in order to keep them motivated to go back.

A few things. The quarians have the opposite amino acid-chirality from humans and most other species. Their DNA essentially just twists in the opposite direction from the way other species do. They share this trait with the turians in that both are, from a biological chemistry standpoint, minorities. So garden worlds are already rare and the quarians need to find what is rare among rare things. Even  if they did, the turians would naturally have the great weight in terms of economic, political, and military power in pushing their claim to it. The galaxy is not fair, especially not the Council.

Consider it from this perspective: why let the quarians have anything for free if you can benefit more having it yourself? A better question is why haven't the quarians petitioned to become a turian client race? They'd be protected that way, even if it meant giving up their autonomy. Sometimes I wonder why the Council didn't force it upon them but then the Council never does the responsible thing anyway. 

Also, consider that if the quarians settle on a world there is a non-zero chance that the geth might find out and attack. A fleet is easier to defend than a planet or cities on a planet. From a military standpoint it might be judged as very, very risky for the quarians to settle somewhere if the geth are still a threat. That is part of the appeal of the homeworld; get your ideal world back and eliminate the greatest threat to your race at the same time. 


Something to consider about Ekuna and the Terminus systems as well is that the precise location of the Terminus has likely changed with time. I imagine its relative boundaries and overallcoordinates in the Milky Way is the result of several factors, namely the destruction of the quarian civilization and the withdrawal of the batarians from the Citadel. At the time Ekuna was discovered that might have been a stable region of space. 

The thing that blows the dextro DNA argument away though is the fact that the Quarians have been surviving for over 200 years on ships scavenged from other species in space.  Therefore, they have to be able to grow their food on those ships and that means that they should be able to build environments to grow their dextro food on pretty much any planet suitable for general habitation by any of the other species.