RE: Local hobby shop want to teach at our field
I don't see a mystery. It sounds like the AMA agreed that the Introductory Pilot description fit this situation better than the "commercial instruction" description. Since the guy wasn't charging for instruction, it sounds like despite the litigious society, common sense prevailed.
Personally, I think they should just require the student to get the three month introductory AMA membership. If you can't risk $29 this hobby/sport is not right for you anyway. $29 is about what it costs for a couple to go to the movies, and they might not like the movie.