I don't think that's accurate BeeSouriante - GC activists have been concerned about women's spaces, not just toilets - if you've followed the discussions on here, you'll see there has been a lot of concern about protecting the women-only status of rape crisis centres, refuges, etc.
The issue taken to the UKSC by For Women Scotland wasn't about toilets - it was about The Gender Representation on Public Boards (Scotland) Act 2018.
It was trans activists who made the ruling all about toilets - have you seen any discussion of the UKSC Ruling by them - the Trans Legal Project, for example - which does not focus on where they are going to pee? And any lobby or demonstration by them which does not involve peeing?
It is trans activists who demand special toilet provision in buildings, even though it is disproportionate to demand expensive and disruptive 'fourth spaces' for such a tiny percentage of the population, who are physically capable of using the toilets designated for their sex - unlike the 'third spaces' which are actually needed by people with disabilities, it's not just a matter of 'feeling more comfortable' in an accessible toilet.
It is trans activists who have sought, for whatever range of reasons, to overturn the standard format of toilet provision - women's toilet, men's toilet, and disabled people's toilet - as set out in building regs, health and safety regs, workplace regs etc, for without offering a proper rationale for doing so.
Toilets wouldn't be an issue at all if people just accepted that public toilets have always been segregated by biological sex, and it has worked OK - 'the good men stay out so the bad men stand out' - until very recently, when a small group of people started to demand the 'right' to use the toilets designated for the opposite sex.
And it sure wasn't GC activists demanding the 'right' to use the men's toilet!