No, it's good to hash this out. I've had people approach me in the paddock and go off on mine being illegal. I tell them to file papers. I'm confident they are legal (as this thread seems to suggest) and having this type of discussion here helps confirm that and also educate others.
In finding 15X6 wheels, do remember the weight of the adapter in figuring out what you want. I think Spinwerks will cut you a 15X6 wheel at about 10 lbs which may be cheaper and lighter than anything with an adapter.