If it's not an original art (and not something owned by that instructor), I don't see where he has any leverage except any possible contracts signed. As someone else noted, if your son was underage when the contract was signed, in most places it's not valid.I’m impressed with all the great feedback that has been given so quickly. Let me clarify on some of the parts per request.
He, my son, has no interest in copying the name of the school. It’s not that cool to worry about.
He has no interest in copying any designs or logos. My son is an artist and can make his own.
I don’t see how the instructor can hold any claim to the material for the following reasons. My son started at school A. An instructor who taught at school A was fired to the point the main instructor removed all evidence of the instructor working there before. My son decided to go with the fired instructor feeling he was the better teacher. The fired instructor taught the same forms and style as he had learned from School A. School A never came after the instructor for teaching the material. The whole system is from a questionable and / or confusing lineage. It is a hodgepodge of different styles of Kung Fu. Many of the forms can be found being performed by other people not related to the school on YouTube.
If we ever signed a non-compted clause it was very short and made by the instructor not some iron clad type of document. Yet again, since it wasn’t his in the first place, can he really do that?
The instructor felt fine letting me son teach time and time again with him showing up. It was getting to the point where my son was teaching way more than he was.
Also, my son probably will not consider teaching in a business type setting until he finishes school and gets settled. So, potentially, he has 4 more years of studying other martial arts. Can’t he just teach his own style at some point and use a little from each. We already know the instructor wasn’t using his own made of forms.