He was leaving when he was assaulted. Up to the point the cop committed battery no crime had been committed.
So I agree with you that he broke the rule about haveing his student ID with him when using the library and he should face what ever the school's prescribed punishment is for that infraction.
The cops committed crimes. They should be prosecuted.
We are a nation of laws. No group should be above the law.
He refused to leave until he was tasered.
The cop committed battery? Oh, for goodness sakes.
What's the cop supposed to do?
Sit there all night asking him to "pretty please" leave and "pretty please" don't ask others to join your "resistance."
He asked for it, he got it.