It’s towel popping time.
Yep. A perfectly-delivered snap to the perv's naughty bits with a damp rat-tailed towel would do him a world of good. Though he might not think so.
The dads should take this piece of filth out behind the gym, beat the coon dog $h!t out of him and do a number on him with a dull knife. Bet he won’t be swimming for quite a while.