I do think this is an interesting but not unexpected development.
The SC ruling means employers, service providers etc. need to be clear what facilities they provide and who can use them. Signs on the facilities must also be is clear.
From the article, and memory, Portcullis House has clearly signed toilets by sex e.g. women’s and men’s s, plus gender neutral/unisex disabled toilets and changing places facilities. This makes them legally compliant.
I expect RMW actually asked where are the “toilets” rather than the “women’s toilets” and so was directed to the toilets which probably have the men’s and women’s close together.
It is for RMW to respect the law and use either the men’s or the disabled gender neutral facilities. If, as per the article, RMW has an urgent need for the toilets using the gender neutral disabled toilets is appropriate on those grounds alone.
The SC was not suggest employers or service providers “police” access. What they are expecting is that societal norms will make it unacceptable for TW to use women’s toilets.
RMW is looking for an argument they can take to court to claim discrimination. I suspect other TRAs will be doing similar.
The SC has given women the right to challenge but it must be done politely and safely. Which, from the article, that is what happened.
Smoking is a good example of how societal norms changed. Over time an increase in gender neutral facilities and the mantra “good men stay out so bad men stand out” will see it become more and more unacceptable for TW to use women’s facilities.