What is wrong with having two distinct but related senses of the term,
@Elaedith?
Nothing, in principle. In fact, that's what we had up until very recently. Gender was distinct from sex, but very closely related to sex. Directly informed by sex, even.
However, a lot of gendered concepts were held by feminists to be either sexist, outdated, outright misogynistic, or some combination. So feminists began diligently excising these anti-social stereotypes, and deprecating "gendered" concepts altogether.
So far, so good.
Then the TRAs came along, and sought to repurpose gender as completely decoupled from sex, in order to reestablish gendered concepts as the gateway to overriding sex segregation (which they worked diligently to rebrand as "gender segregation").
But now it turns out that gender becomes practically meaningless, when the relationship to sex is removed. So the feminists (i.e., the anti-TRAs) have reverted to sex-based distinctions as such, because those are the only distinctions that matter in this context. And the TRAs, of course, have moved from recontextualizing gender, independently from sex, to redefining sex itself - since sex distinctions are the only distinctions that actually matter in this context.
Personally, I'm fine with having two distinct but closely related senses of the term. However, that's with the feminist caveat that most gender-oriented terms and concepts should probably be deprecated anyway. All that really matters is sex, so when I say woman, I mean adult human female. And when I think of women as distinct from men in society, I think in terms of the biological distinctions between the two sexes, not the stereotypical gender roles formerly (and in some regrettable cases) still associated with the two sexes.