The school probably has a mandatory policy for placing employees on leave when police are involved. That makes sense to me. Look at it this way: if the school has to make a choice and they choose not to put the teacher on leave, they may get sued or get in a lot of trouble from parents by leaving a potentially dangerous person in school. On the other hand, if they choose to suspend the teacher and the teacher is later exonerated, they may be looking at a lawsuit from the teacher or the union for defamation, discrimination, you name it. If the school lacks the discretion not to suspend the teacher, though, they can't be sued for anything like that because they're not taking a potentially problematic action. No teacher is going to be able to say, "you put me on leave based on my race/sex/whatever," or "you irreparably and unjustly damaged my reputation by choosing to put me on leave." The real test for the school is how quickly they can resolve this mess and get the teacher back into the classroom.
Side note, but education-related: just read a
case where a student appealed a suspension based on their First Amendment right to wear, get this,
Big Johnson t-shirts. Thank you, early nineties.