Re: Uncooperative participant
I think you have a good reason to speak with the park and rec and explain that this kind of behavior is not acceptable for your dojo. if it was another sport and someone new came to play say basketball and insisted on changing the rules, that wouldn't be acceptable.
a side note, at my dojo, sensei's son usually teaches when his father isn't there, even thought there are a lot of people who out rank him. everyone seems happy enough.