I think the skipping school for a week w/o permission would be the reason.
Could be, but something tells me if he was an anti-war activist who "went on his conviction to stop the bloodshed" there would be a pep rally welcoming him back and congratulating him for his "strength of conviction". Of course, since he's on the other side of the coin, it's "straight to the principle's office mister right wing war-monger".