If the mind game is meant to be something like therapy for trouble super-geniuses, then here we’re given a slightly different purpose for manipulation: the school administrators are messing with Ender in order to make him the best he can be. (This is probably Anderson speaking.) Note that here, the manipulation is not just for the benefit of humanity – it’s not just that Ender is a tool. The speaker also thinks “this is best for Ender.” So here we have a slight defense of manipulation.

This nicely contrasts two areas where Ender is at war: he’s at war in the battleroom (in the game) and he’s at war in the rest of his life (with the other kids). According to this quote, Ender is more vulnerable in the rest of his life than he is when he’s playing a war game. So in a strange way, Ender seems safer when he’s fighting a war…

This is Carn Carby, showing how to be gracious when you lose. Carby thinks the other captains are being jerks because they aren’t recognizing Ender’s win. What’s curious here is that Ender won the game, fair and square. As Carn notes, though, that win doesn’t translate into respect in real life, because life is unfair. (At least, that’s what people usually mean when they say “that’s life.”) So there’s some way in which the game is set apart from regular life.