The judgment is quite clear on this.
If you are applying a single sex exception - ie that your organisation is women-only - you can only do this while you exclude all men.
Once you start including some men, you are then discriminating against all the other men. Because the exception that created the group was sex based, not 'women and men with'.... which creates no coherent group in law. And let's face it, it's already in all honesty the 'women and any man who wants to self ID institute'.
They either have to open themselves to all of both sexes who wish to join and re write their consistution and organisation name, or apply the single sex exception. One or the other.