This guidance absolutely nails the problem and closes the loopholes and all the whataboutery.
It is comprehensive enough to cover all of those.
Yes, some people might not like it as evidenced on this thread 👀 but it is very clear that single sex spaces mean single sex. That's it.
It is perfect for certain circumstances we have seen in real life:
RMW facing the choice of doors right in front of him - male, female, gender neutral - chooses the female toilet. He was, quite rightly, challenged on this. Because he is male. Why does he or anyone else think he has the right to use female only spaces.
Eddie Izzard queueing for the female toilets. Eddie self identifies as gender fluid. When asked in 2019 what pronouns he preferred, Izzard responded, "either 'he' or 'she'" and explained, "If I am in boy mode, then 'he', or girl mode, 'she'". Eddie is male. Why does he or anyone else think he has the right to use female only spaces.
India Willoughby boasted online about ignoring the nearby gender neutral toilets at an airport and instead walking further out of his way to the female only toilets. India is male. Why does he or anyone else think he has the right to use female only spaces.
No one is saying these men are a threat to women. They are simply saying they are not entitled to use female only spaces because they are not female.
Therefore they, like every other male, must use the male facilities, or the mixed sex facilities.