This sounds like a good idea, i wonder if its do-able.
My son is 11 and is hooked and he does pretty well. I let him use my account a couple weeks ago during spring break during the day while I was at work. Problem is I can't get him to respect a planes stall speed. He thinks he should just be able to point the plane up and climb forever. (hes getting better at it) And because he likes to fly the planes I fly (D9, La7, F4U) these planes stall easier than some other planes. I don't know how many kids are out there that would want an arena like this. Relax the realism on some of the flight model, maybe double the ammo loadouts, smaller maps, fewer fields, and an age limit say 15 years. Of course the other answer is find a boxed flight sim that has unrealistic flight models and fantasy loadouts.
On the other hand, maybe he can just suck it up and learn to fly a sim the right way with correct (as possible) physics and learn the hard way, with lots of practice and perstance.