You are being too absolute, imo.
First, we do not know all the circumstances.
Second, how do you know it is a "reaction" and not some genuine issue of removing the child from a situation that was just going to get worse, not better, including for the child?
Third, what alternative does he have? He was evidently called in to the classroom by the teacher because this kid is acting out and has kicked her. Is he supposed to just scold the child? Walk away and let the teacher continue to be abused? If he calls the principal, what difference is that definitely going to make?
I'm also a little skeptical of the explanation that the kid just threw a tantrum and kicked a teacher because of sleep apnea. Seems like it might make a kid cranky, but its going to make her tired it seems to me, not amp her up.