As a teacher and former coach and administrator... he's gone. I could care less what his reasons were or if it was "the heat of the moment" or any other bunk people like to throw around. He's gone. End of story. No questions. No appeals. Call your lawyer mom and dad if you want to fight it. Any district worth a crap will back me. I'm the coach, and I never want to see him take the field for my team again, and if I am his teacher in any classes I ask for him to be transferred out because I don't want to deal with it and I can't respect him (sorry, that's harsh, but sometimes kids reach that age and you have to ask some hard questions, and this kid answered them). As an administrator I suspend him immediately for what is allowed in this state (five days while an investigation is conducted) and then he's in front of the school board next Tuesday fighting for his life to even be allowed to attend school. I'd push for a board release as a coach and teacher, and as an administrator I push for the same thing.
I actually taught a kid like this. Did a lot of the same crap. We pushed for what I suggested above, and that is precisely what happened. He was removed from the district, and it was the best thing that ever happened to the kid. His father was the football coach and refused to take action and he was fired. It was also the best thing to happen to the father.
The father and his three sons all attended anger management and family counseling of their own accord. The son couldn't enroll in school for two years. But re-enrolled in another district two years later as a senior that was granted an extra year. The father also was hired as a teacher in the other district, and both of them were changed MEN (finally... prior to that they were having regular fights in the yard and police were there CONSTANTLY but nothing happened because Dad was the coach of the juggernaut team, and the son was the star QB, but had literally attempted to kill multiple people... including the principal who he had choked unconscious as a SIXTH Grader and my mentor rescued the principal and gave him CPR... kid was still in school for 4 more years before being excused by the board).
Honestly both father and son (and the other kids) needed to face the fact that something was seriously wrong with them. The dad was a tyrant and was raised by a complete SOB abusive tyrant. The sons became awful human beings. Seriously. AWFUL. Evil kids that really (this is the only time I've said this about a kid) had no redeeming qualities.
Dad and sons took the punishment seriously, owned up to it. Dad didn't attempt to coach in the other district, just teach (and he was a decent teacher, but skated by on sports success and didn't give the effort he was capable of at the teaching portion).
After moving to the other district the son played football and the father helped coach him and the son actually ended up earning a college scholarship as a QB and played at Southern Utah and had a good college career and last I heard he had married and was happy and living a good life. It took a punishment (a serious one at that) to make them all pull their heads out. I'm glad it came to that before they all ended up in prison.
With this young man. No tolerance. Look a bit deeper. Kids that do this crap rarely have well adjusted home lives and such. There is a kid with some serious anger and self control issues. No... I'm not blaming his parents. But many times with this kind of behavior, there is a reason, and I don't buy that it is heat of the moment and he is mad that somebody pulled a cheap shot or whatever. I got a cheap shot in games a couple of times (once blowing out my knee). I was ULTRA competitive, but I NEVER let it escalate to the point where I retaliated, because I had some self control and was aware of the whole right and wrong thing and let others suffer consequences for what they did and tried to take the higher ground. This kid needs to go and the coach needs to lead the charge, even if it is the greatest player he's ever coached.