The whole "women aren't who we've always believed, some people we thought were men are actually women because..." schtick is a red herring when it comes to women-only spaces / opportunities / resources / representation anyway.
It doesn't matter whether the new definition of Woman is "still biology but it's complicated", " just a social construct anyway" or anything else.
It doesn't even matter if all the "women" under this new definition really do have something significant in common with each other that they don't share with any "men".
What matters, the thing that it's crucial to keep sight of, the thing that all the TRAs' twisting and turning and TWAWing is desperate to hide, is that Woman-only provisions weren't set up for the word Woman. They were set up in response to and shaped by the needs of specific people.
And who were they? They were the people who met the everyday, common or garden understanding of woman at that time.
It doesn't matter if that was a flawed understanding, it's still the people who met this definition who suffered the challenges that created the need for and shaped the form of women only provisions. Not transwomen, not people who meet a deeper, less obvious definition of biologically female we may now have.
And that truth doesn't change just because you retrospectively change who the word Woman points to.
Of course, TRAs would counter TW should have been included. But if TW had been included back then, the challenges would have been different so the shape of the provisions would also have been different. The reality however is that they weren't, so to add them now is to muddle up two definitions of Woman.
Of course, this isn't a logical path TRAs are going to be motivated to follow. But it's one that gender critical people should see clearly. At the end of the day, arguing about the definition of Woman isn't the point. In some ways it's letting the TRAs set the terms of the debate.
The real question TRAs need to answer is how can TW's "womanhood" qualify them to access "women's" resources when those resources are only "women's" under a definition they reject.