Sarissa Theris: Pathfinder, or Exile

Without the scourge data stolen from the Kett, the Leusinia probably wouldn't have survived for how long it did. The ark would have been destroyed by entering a scourge cloud or have been too slow to navigate around the scourge tendrils so that Kett forces could have taken over the ship long before Ryder and team arrive.

So imo taking that data was right, and it was more important than their active Pathfinder. So i most often keep Sarissa as Pathfinder, but tell everyone what she did.
Most of my Ryders believe in owning your mistakes and actions, and expects the same from others - Especially those in positions of power.

I have made different decisions in various playthroughs. My first playthrough is typically my personal 'canon' playthrough, and I personally like telling everyone what Sarissa did, but also keeping her on as pathfinder.

My opinion: I do not know if Sarissa made the right or wrong moral decision, but I think she made the correct tactical decision. Regardless, I think she deserves a second chance, the same second chance that Ryder may need at some point in the future. Ryder is trying to set an example for future pathfinders and the Initiative/Nexus: own your decisions/mistakes and make them known, but also provide a path for forgiveness and second chances.

Whatever tactical value that data had, it was also the reason that the Leusinia had to keep escaping the kett. If not for that, the Leusina probably could have made it to the Nexus on its own, same as the Hyperion. If the Hyperion hadn't made it, Sarissa's actions could have doomed the entire Andromeda Initiative. She doesn't get to just walk away from a screw-up on that level.