//...but could you for once try to imagine yourself in someone else's shoes//
I certainly can. I can imagine being a young woman who has spent, perhaps, ten years or more of her life, getting up at 6am four or five days a week to get down to her local swimming club, training before school, then more of the same in the evenings at at weekends. She begins in local club contests, graduates to perhaps county level competitions and then national contests. Then she sees a bloke like "Lia" thomas come along and enter her chosen events, clearly a man with all the physical advantages that men have, and she realises she has absolutely no chance of reaching the top step of the podium. That's the sort of empathy I have.
The young lady whose shoes I put myself in has no more choice in her gender identity than one who "...does not feel that they are a man or woman despite what their bits are like," So tell me, why should my young lady suffer her misfortune (shared by more than 99% of her fellow women), but your man, who wants to pretend to be a woman, shouldn't? Why should he insist in competing with people over which he clearly enjoys such an unfair physical advantage? A separate competition for him and his like is the answer.