Originally Posted by
Douglas
Because its primary motivation has nothing to do with its own survival, or the survival of the Reapers. It is trying to solve a specific problem, currently has only a temporary patch job solution, and that patch job is failing. You getting to where you are is not some incredible fluke, or at least not just that, it's the continuation of a general trend - cycle after cycle, the design for the Crucible gets discovered, refined, improved, and hidden away for the next cycle to find, while attempts to build and use it get closer and closer to success. The Reapers failing, and failing soon on the time scale of their cycle, is inevitable. It needs a new solution, it doesn't have one, and it's not likely to come up with one before the Reapers get outright defeated. If you pick Synthesis, that's its perfect ideal solution from its perspective. If you pick Control, then maybe your fresh perspective will think of something it did not. If you pick Destroy, then at least the organics of the already technologically advanced current galactic civilization will have some breathing room to figure something out, with all existing synthetics gone.
The Reapers are the only AIs that Shepard has encountered that have been violent without provocation. The Star Child's goal and logic is based on millions of years of history, against which the current cycle is one tiny blip on the record.
The premise is based on facts that you cannot verify, not false. The conclusions are observations of facts that you cannot verify, not purely logic, flawed or not. The Star Child's goal is not to protect organic life, but to protect the existence of organic life - to prevent 100% genocide of all organics - and if it allowed organics to develop without limit then they would eventually develop technology capable of producing synthetics that the Reapers are unable to stop.
The Star Child has a great deal of historical knowledge that you do not, and a set of values and priorities fundamentally different from yours. That is not the same as it being insane or divorced from reality.
Finally, if Control is a trap, then why wouldn't Destroy also be a trap? The choice isn't really "Control, Synthesis, or Destroy", it's "Action A that will supposedly result in Control, action B that will supposedly result in Synthesis, or action C that will supposedly result in Destroy". Yes, the Star Child doesn't verbally tell you what the actions are, but you see visions of them as it's describing the outcomes, and the only way Shepard could know what to do is if those visions aren't just an out of character thing to inform the player. If you don't trust that at least something the Star Child told you is true, then you don't even have the ability to choose an ending at all.
The Reapers have not been trying to genocide the entire galaxy - they only target spacefaring races. There's quite a bit of evidence from earlier in the series that this isn't just a matter of not having gotten around to the rest yet, too. The Asari, Salarians, Quarians, and Yahg all already existed in the previous cycle, and were all left untouched even when the Reapers gained total control of the galaxy and completed the cycle.
Indoctrinating Shepard at an earlier point, especially at the start of ME3 or before, would indeed have been an incredibly valuable achievement. At the point of meeting the Star Child, however, it would be entirely superfluous. The pan-galaxy fleet is already assembled, already there, and already locked in battle with the Reapers, it's too late to derail that. An Indoctrinated Shepard would not meaningfully help the Reapers win that battle, and once the battle is won then there's little use for him because the resistance forces committed the bulk of their military to that single battle. It's a case of a single battle deciding the war, because whichever side loses will have too little left to continue to pose a threat. The window of opportunity for Indoctrinating Shepard to be useful has already passed.
And if it is an Indoctrination attempt regardless? Then you can't trust that the "Destroy" action will actually do anything you want, much less what the Star Child said it would, either.