I don't think the story works as well when you subtract the torture and child on child murder. Subtract swear words with childish booger references all you like, but war is hell and 'the chosen one' for interstellar is the kid who instinctively knows to kill the giant by biting through his eye; but remains sociable enough to be a general leader. The reason Peter failed in being selected for the the role is he had part one without part two.
One quibble: At worst those were episodes of manslaughter. He didn't intend to kill them, just hurt them enough to send a signal. Unfortunately, as a child, he was unable to gauge just how much force he was applying.
Peter failed because he WAS willing to murder people. Ender was not- it was just an unfortunate consequence of trying to stop them.
It's the idea of shooting to stop or shooting to kill. Ender did what was necessary to stop the threat. (Sometimes that would involve killing). Peter would have killed to stop the threat, whether or not that was necessary.
A fine distinction, yes, but I think important. It wasn't "remaing sociable", it was a matter of the heart. (Remember, they had an implant
reading his thoughts... Card never really got into that, but THAT was some freaky tech he never fleshed out.)