I use the term 'him' as it gives you an idea where he came from. He was a gung ho army type when he was younger. I have no problem with him, last time I saw him was with his rig parked out front of my mother's place. But when it comes time for 'him' to wrestle another woman to the ground 'she' (feel better?) will probably win. No, I do not call my cousin him, her, she, they, I use the name I was told she goes by now.
I think in terms of gender as in how many chromosomes a person has. Whether they grew up learning how it is to be a girl or a guy. Not a lot of guys get periods every month, a woman or man's body talk to us differently whether or not the wrong spirit ended up in the wrong gender's body. On my cousin's disposition, he still acts like a guy but with boobs and a dress on. He must still have male longings, he hooked up with a woman after he went through the whole process.
What has being a pro got to do with it? The whole problem really came about in high school sports from what I recall. No, no guy is going to change in order to get a trophy. But what does it do to the other females having a trans person win? Sure it may have some of them thinking it is unfair. And who said if you are transitioning that life would be fare and you get to play sports against other women? I have no problems with a person wanting to change their gender. But I balance that against the women in sports. Except race cars. That is a sport I could see them compete equally.