It's not clear to me just what is being done here. Is the (invented and nonsensical) problem that biological men, currently identifying with and impersonating women, have been prohibited from Whiffenpoofing? (And vice versa for the women impersonating men?) That's hard to imagine. But ... were they expected to wear tuxes, apparently the group's usual uniform, and thus look masculine? If all that's at stake is letting the female impersonators wear a dress on stage, I don't suppose it will make any musical difference. And again, vice versa for the girls' group.
When I sing baritone, I sound more like a baritone, but you can still pick out that there's a woman singing.
And I have a relatively rare voice - true tiefer Alt, range about C# in the bass clef to C in the treble. I can sing a limited number of Es and Fs in the treble, but I'm really in my falsetto and my account gets overdrawn pretty quickly.