I expect this is a debate that will go on and on for some time. The only thing I'll say at the moment is that (with the possible exception of state-sponsored programmes in the mid-80s) no-one is going to "choose" to switch their entire gender and corresponding lifestyle just in order to have a possible edge in athletics events. Which in turn means... well, where would athletes who happen to be transgender compete? Seems mean to call a transwoman athletically a man (or vice versa) as that says that you don't accept their identity; and, equally, it is true that transwomen are likely to have some long-term biological advantages over other women.
The whole thing is a mess, but they have to compete somewhere if they're wanting to become athletes. It's further complicated, incidentally, but the possibility of non-XX women or non XY-men in terms of genetic code, so they too would have potential nightmares trying to compete.
In the long run, I think that athletes should be allowed to compete as their assigned gender, though. Even if transwomen might gain some advantage from their biology, that isn't going to give them any hope in hell of winning on its own. They'd still have to put in the effort, training etc, at the same level as any other athlete.