That was kind of the Scottish government's case wasn't it? Except they went with having a GRC not having surgery. I don't think most TRAs even realise that their 'side' had already agreed that non GRC holding transwomen were not entitled to be considered women. And that therefore even if FWS had lost the vast majority of them would still not be lawfully permitted in women's single sex spaces. Self ID was over either way on paper (though in reality would have been impossible to police).
I believe that's why Stonewall et al didn't apply to intervene, because their arguments would have had to be that GRC holders were 'proper trans' and the rest weren't. Which isn't what Stonewall et al had spent the last 15 years lying about. TRAs would have tantrummed and all the businesses and public services that Stonewall made money from would have said 'oy that's not what you made us put in our polices, what are you saying?'.
Stonewall expanded the trans umbrella and 'truscum' got pushed down the totem pole, but in the case 'truscum' were the only transpeople under discussion. The TRAs who are actually capable of understanding the judgement will eventually realise that and then there will be fireworks.