Actually, you bring up an excelling additional argument for the sort of bracketing I proposed. It also works for drugs!

There is significant grey area wrt to "doping" too in the sense that a performance enhancing drug may express as a larger than normal amount of a naturally occurring substance. So did the person dope, or is that their natural genetics? In my scheme, WHO CARES!

Beyond that, I suppose there is the usual argument against more serious and non-natural forms of doping that it is physically detrimental to the competitors and by allowing it you are encouraging or pressuring people to essentially harm themselves.

Still, competition classes could be helpful in some of the doping grey areas.