That's the exact opposite of what I'm suggesting up-thread.

Categories would be assigned based on performance criteria for the sport in question. One simplistic approach, loosely modelled on how road cycling works, would be to have categories based on race performances - you enter an "open" category, and after N finishes above a certain level, you are required to move up to "division 4". After N finishes above a certain level in div4, you are required to move up to "division 3". And so on. The idea is that you're racing against your performance peers, regardless of their gender (or age).