I believe the reason the local club has this rule is because the president of the club owns the only hobby shop in town.
So if you can only learn to fly on a trainer then you have buy another plan after you learn to fly. Needing another plane means there is a very good chance you will go to his store to purchase it which means he gets to sell 2 planes instead of one.
I could be wrong in my opinion, but that is what it "smells" like to me.
Only thing is, with this silly rule, I will not purchase either of my planes from his store.
As far the engine in the Tower Hobbies Trainer, although it has Tower as the name it is actually an OS. Just like the Tower radio is actually a Futaba with the Tower name. This what the guy at Tower Hobbies told me. He said companies do that alot with companies who buy masses from them & also contract with them. Just like the LXI series of TVs & stereos are really Magnavox.
If I could find a great deal on the Avistar RTF I would get it & just a club in a different town even it means driving 60 miles. *Ü*

Thanks for your help,
Paula