Like I said that is the only issue and its between him and his employer.
There may be some ethical issues beyond the employer relationship, such as those mentioned in post #22. The school district may have legal options here. Superheated topics like this generally don't have all the facts - but I think that both men - the teacher and the cop - are engaging on problematic conduct while conducting public business, and both should face some kind of sanction. I imagine the cop's bosses will do their job. If the school board does not do theirs regarding this teacher, then folks should work to replace the school board.