I just realized that you must all be referring to a Male "trans" boxer fighting a female? I wasn't aware this was the topic.
Either way, I think sport should be a meritocracy, not gender segregated. Fights in particular should be accepted on a case by case basis. Like McGregor VS Mayweather. People could argue that that was a "Boxer" beating a non boxer. But they both agreed to it.
I think if the natural born women agreed to fight a trans guy(assuming she knew that he was trans). Then if she gets her ass kicked its on her. Nobody was complaining that Mayweather kicked McGregor's ass....he signed up for it.