There is nothing wrong with flying on school property if you have permission. I flew on school property for my first 14 years in the hobby. In fact I taught people to fly models at a nearby commuinity college for 8 years, (with the schools knowledge and permission).

We all had AMA memberships and we all adhered to the AMA safety code. Parties interested in joining the hobby were informed about the AMA and about the liability associated with the hobby.

Your post seemed to be confusing two seperate issues : 1.) Informing new pilots about the AMA and 2.) flying at non-AMA locations.

It is completely acceptable to fly at non-AMA sites if you choose to do so. But you should join the AMA and always fly by the AMA safety code.