" It is supposedly impossible for a cis girl to defeat a trans girl in a fair contest, and unjust to make them try. "

Why don't women compete against men in boxing? Sumo? The 100 meter dash? Golf? Because in a sport that requires speed, size, or strength at the highest level, the BEST men can defeat the BEST women. How the also-rans fare is entirely beside the point.

So spew the non sequiturs about variation within groups is you must, but, when you're done, tell us what woman could outrun ANY of the finalists in ANY men's Olympic race, which woman could beat any member of the US Tennis team or boxing team or golf team. Yikes.