Here is the issue for me: more than once I have been creeped out by someone, only for the person later to be in trouble with the law for what they did with children more privately.where was there ANY mention of sexual abuse. OP said her child is creeped out. Being creeped out is nothing more than being uncomfortable. Unless there is a reason the child should be creeped out, I suggest it is simply a matter of the home teachings conflicting with the apparently legal activity.
but I do have a question; why is the coach showering? They typically do not engage in the physical activities the student does.
Personally, I would not shower in front of the kids. To me it is a matter of an established hierarchy being ignored. It changes the way a coach is perceived and, to me, it diminishes the level of respect the coach can demand once everybody has seen him naked.
So, LEGALLY, OP has no issues - there is nothing to address LEGALLY. Being creepy isn't a crime. We don't know if OP's son's uneasiness is based on bias or intuition. OP's son being uneasy around coach pretty much ensures that he doesn't trust the coach, won't want to be alone with the coach. OP complaining to the principal guarantees that the coach, unless he is a complete idiot, would not be alone behind closed doors with OP's son.