This.
It's a very useful lever for slightly timid members of staff, governors, parents who didn't want to be branded transphobic bigots to say 'safeguarding requires single sex facilities to mean single sex' and to be a bit braver in standing up for safeguarding and against bullying (because inserting a boy into the girls facilities is bullying of the girls).
Honestly don't know where schools who've been forcing girls to undress in front of male children will hide. They're failing to safeguard and acting against KCSIE if they do this. It's a massive safeguarding failure.
Surely @SingleSexSpacesInSchools your case is slam dunk now? It always should have been, really, but here we are.
I also think this idea that on the one hand there's so much about bullying in KCSIE but the idea that boys might pretend to be 'gender questioning' to bully and intimidate the girls is never even entertained is woefully naive. And indeed the stuff about 'emotional abuse' is in there but the idea an adult might specifically get a job in a school to bully and coerce children into their pet activist cause, or 'affirmation', as we know has happened, is also woefully naive.
Far from ideal - the bit about pronouns needs to be far more explicit, including the coercive and emotionally abusive nature of any request to compel language against normal English - but also far better than before.