If a woman, trans or otherwise, wants to participate in men’s sports, why not let them?

They are welcome to as long as they are not using performance enhancing drugs like testosterone. The problem has always been when you have men competing against women. Not the otherway around. Women already can try out and compete if they are good enough in the nfl. But none of them are.

If a woman, trans or otherwise, wants to participate in men’s sports, why not let them?

What are you not getting? There's nothing stopping them except biology.

And so there’s a WNBA where women get paid less, have a lower viewership rate, and are repeatedly told the sport pales in comparison to the NBA.

Oh the horror, they are told the truth. If it was just as good as NBA the viewership would be just as high, but it's not. I'm sure they take a larger cut of the revenue than the male counterpart, just like they do in Soccer. So they are actually overpaid.

even if they’re “too weak”?

Have you ever done any physical activity at all? If you did you would know that strength and other biological factors simply makes it impossible for women to compete against men.

I'm not sure why you confuse physical strength with brain power.