And that as other races have different genetic bone density if the argument against transwomen in women's rugby is down to bone density then white people shouldn't play against Japanese teams. And so on.
Ahem, a phrase that I acquired from Kathleen Stock (Chapter 4 of Material Girls) and Jon Pike of OU (heavily involved in the ethics of sports and women) feels relevant here, homeostatic property clusters.
If you claim 'woman' is about identity, then people will retreat to 'female'
If you then claim that there are 'female penises', people will retreat to "a homeostatic property cluster of XX chromosomes, large gametes, testes and circulating testosterone with such and such reproductive function."
Or, stop reducing women to single features/variables and pretending it's all about that. It's about male puberty and the cluster of physiological properties that it creates of which bone density may be one part alongside the relative size of the heart and cardiovascular system, explosive twitch fibres in muscles etc.