Ok, so just as a head's up, we don't have a running list of what poster has beef with who and what exactly that stuff stems from.
Bystander's account, the comment was completely innocuous. You were the one who threw the barb that is strictly against the rules.
So essentially he's the kid that called you short and you threw a punch in front of the teacher. Of course you're the one who got in trouble. Being called short isn't a reason to throw punches young man.
Ignore it and move on.