To exclude one sex you have to invoke the SSEs
In fact the SSE as currently written is no longer relevant as it was specifically about saying men in a GRC in this instance (SSE) they had not changed sex.
In the future, much as the EHRC did when it described how to advertised a job that was only for one sex, you had to declair it (and why)
The SSE is now irrelevant as it was Labour admitting they had wanted to make a man with a GRC a "legal woman" and the SSE was for the occassions he wasn't.
So now that the word sex means biological sex, it is more about on what basis under EA you can "positively" advertise to only one sex.
There was a thread on this as the EHRC only recently updated it.
Though I think many of us thought it was clear as mud, and think now that I remember it I said what I said at the time. Why cant you just have a simple foot note saying this means only X or Y sex!