Originally Posted by
VeloZer0
It doesn't seem obvious that Fal'Cie can't kill other Fal'Cie at all. They just can't go against their own function (which included their continued function). If they made a Fal'Cie that had the function of killing Orphan, well...
Also, why wouldn't you take humans that actually had a desire or predisposition to destroy Coccon in the first place? I could understand if they were in a rush, but they had literally hundreds of years to plan this out. Why would they act if they weren't in a rush?
The plan with the cavalry sounds like a half baked way to get them back to Coccon, indicative that their plan was completely falling apart. Of course anyone should have realized that it was completely obvious that is what would happen if you took a bunch of random people and told them to destroy the world.