I'm going to repeat this:
In effect the impact on multiple women needs to be taken into consideration versus the impact on one male - both argue its an affront to their dignity and privacy. The women also are arguing about their safety and concerns about harassment. All people being equal you act so there is the least impact on the fewest people.
Which part of this do you have a problem with? Why are transwomen and women not equal in their right to privacy and dignity? Why when multiple women, who lawfully do not believe you can change sex, have to share with a male? Why do their safety and concerns not matter? Why must multiple women be potentially harmed for the benefit of one male?
The solution is to provide a third space discreetly to protect the privacy and safety of the male.
This is not hard to work out and administer.
Then if that member of staff is harassed in any way, you THEN deal with it using the appropriate channels.
Validating his identity by allowing him to use the women presence in the same room and forcing others to go along with it, is not compatible with Forstater.
If he 'just wants to get changed', then let him change. He does not need the presence of the women to change.
Women are not there to be support humans for males who want their identity validating.