A general comment, not just on GG:
Even if you believe that womanhood or girlhood are states of mind rather than bodily facts, it is undeniable that most of the long-standing women-only or girls-only provisions were created with the assumption (or if you prefer, misassumption) that women and girls are a single sex group.
And because they were never set up with a mixed sex group in mind, they don’t necessarily have appropriate structures and processes for mixed sex groups.
GG, for example, when they thought about their residential or camping rules and guidelines, simply never had to consider that some teenage girls can get other teenage girls pregnant.
So what I don’t understand is why, now all these groups are deciding that women, or girls, actually are mixed sex, they aren’t starting by going back to rethink and where necessary change what they do to fit that mixed sex model. If, as they seem to believe, we were wrong about what a woman or a girl is all this time, why on earth do they assume everything set up under that wrong definition is still right for the new one?