The long debate over whether MWMF should allow transpersons seems to me to be part of the same issue.
If I were running MWMF, this is what I would say: No penises.
MWMF is about women who are oppressed by men every minute of every day being free of that oppression for one week of their year or possibly their lives, and reveling in that and celebrating each other.
But if you can't set your male privilege aside, as well as your penis, then MWMF is not the place for you, and your presence will harm other women who, like me, have been brutalized by men.
And no one should be checking genitalia at the door of MWMF. As someone who's spent years experiencing bi-genderism, I understand why transwomen would want to attend MWMF.