But I am confused about the idea that a PC cannot be self id into. How else can someone have the PC of GR?
I think that's his point. That a PC shouldn't be something you can self ID into. It's an argument against the existence of the PC of GR.
I would love to know what the intention of the PC of GR was. Was it ever to be allowed to change sex on documents, preferred pronouns?
Changing sex on documents is due to the GRA not the EA. Although sex can be changed on some documents without a GRC, it's still nothing to do with the EA.
The EA is about discrimination and about equal and fair treatment of people with different PCs. If someone thinks they have been treated unfairly because of a PC, they can make a claim against the organisation.