I'm certain that Mouncey and other trans women are already permitted to compete in men's competition. I guess Mouncey's argument against this approach is that she is a woman, and so shouldn't be forced to play in a men's competition/excluded from a women's competition.What about allowing Hannah (and other trans-women) to compete (only) in men's competitions?
What are the arguments against this?
I think the best response is just to emphasise that the women's category is based on biological sex, not on gender identity i.e. we have separate competition for women because of the on average physical differences between males and females. Even if Mouncey is a woman, she is not a female; hence, she is ineligible.