But in order to create a single sex space (which is discrimination) you have to be able to explain your reasoning for excluding the opposite sex.
Girl guides had a single sex space, based on whatever arguments they used, but then opened up that space to a small, selected group of men and boys.
They are therefore no longer covered under the single sex exemptions.
The upshot as I see it, for them and all other groups who have claimed the right to be single gender-identity based, using the EA rules to allow them to discriminate, is that they can no longer justify their position. They are discriminating illegally and leave themselves open to challenge.
What strikes me is that there are going to be a whole load of groups doing this, who ignore this ruling and carry on as if nothing has happened.
And the women who want their rights back will now be faced with having to bring strategic cases against these groups, one by one, which we will win, but which will still take up precious time and money that could be spent doing other things.
Eventually it will come to be recognised as too costly to adhere to gender identity instead of sex, but I fear these organisations will not give up easily.
See also all women’s spaces where they used the EA rules to advertise jobs for women only, but explicitly stated that same, small group of men would also be considered. Illegal, all of it.