If all of a person's official and identifying documents are in the wrong sex it makes it very difficult for anyone seeking to maintain single sex services and spaces to actually challenge anyone who appears to be the wrong sex accessing or attempting to access spaces.
Even if you know that the person in front of you is a man, if all his identity docs says he's female, what do you - as a hypothetical frontline worker, maybe working reception at a community centre when a women's DV group is running, or working the changing rooms in Primark, or doing intake at a women's hostel - do when you refuse him access because he's a man and he says "I'm not a man, I'm a woman, look, I've got a passport, driving licence and birth certificate that all say I'm female"? How do you deal with that? If all the docs say he's female, how do you challenge that?
How the GRA and EA2010 interact has not been properly explained at all and can't be until sex falsification of documents is ended. It just can't. The SC are not on the frontline, they made legal arguments. The EHRC are supposed to make the practical guidance, and I don't see how the SC judgement can be fully and properly implemented until the GRA and it's fripperies are gone.