In fairness, Bobby Riggs was 55 years old, BJK was 29. We'd frown on that if they were dating, let alone athletically competing.
I think the "women are just as capable as men" argument is a dead end, because it's wrong. Not all of the time for every sport, but for most of the popular ones.
From what I have been able to glean from a public debate I don't follow much, it seems that more and more leagues are handing out two medals in the case that a trans person wins. That solves the problem in its entirety. What remains is the bigotry.