I've helped for a few years at the local playgroup sports day - at 3 the boys mostly are en masse out running the girls with a speed and strength they don't have, and staff quietly 'fix' the mixed group races to put the fast boys in together with the occasional couple of very fast and athletic girls, and the slower boys in girl-heavy races so that the girls don't have the endless experience of mostly losing to boys. Otherwise they do get discouraged, and they do perceive unconsciously, even at this age that competitiveness 'isn't for them'.
We see in gender ideology all the time this belief that girls and women are just props in male lives; a part of the resources and set dressing for the male experience, and this is where it starts. We have to get more alert to the messages given to girls that mostly are happening through wholly unconscious sexism and just not valuing girls as we value boys.
Why should the feelings of one boy, and his need to not be confronted with the fact that he is a boy, be more important than the interests of every other girl in his year? What message does that send?
Yes, it's very hard and uncomfortable (and lets be honest, this is mostly about adults wanting to save themselves uncomfortable and upsetting conversations), to have to gently explain to a boy with gender confusion that he cannot be a girl in all ways as he wants to because he is not a girl, but frankly that conversation is going to have to happen eventually. To avoid such a conversation (and likely with shouty and legally threatening activist parents too) schools have enabled shared toilets, dressing rooms, showers, sleeping accommodations - there is no line of the girls that isn't crossed, to the point of active safeguarding risks that would never normally be considered.
The SC has taken away the ability to hide behind girls just not mattering very much compared to a boy. Schools will HAVE to now draw lines, and it is much easier to help a boy within clear expectations from day 1 that while additional and different resources might sometimes be provided for him, he cannot have the girls' resources and that there are limits to how far a transition can go, because of other people's rights mattering too.
It is a whole lot kinder to teach this from the start at primary than the situation we are now in where there are very angry men who have never encountered a 'no' before, have been strongly enabled to believe that they matter and no woman does and that 'no' is a word they have exemption from, and really don't know how to cope with it.