I am intrigued by the concept that the issue with Susie (partly or wholly) is that she’s not trans. They’ve previously made it very clear that they disagree with the EHRC’s position on the Equality Act’s provision on single sex protections and spaces- they are adamant that gender identity can and should be subbed in where the Act refers to a persons sex. (“They” being Mermaids legal team, though I don’t know who that is). They disapprove very thoroughly of any attempt to boundary single sex spaces by using biological sex as a differentiator.
mermaidsuk.org.uk/news/single-sex-spaces-know-your-rights/
mermaidsuk.org.uk/news/our-analysis-on-the-ehrcs-single-sex-spaces-guidance/
So I’m curious as to the mechanism by which they propose to (legally) ensure that the leadership team of Mermaids are trans- they are very keen that the “proportionate means of meeting a legitimate aim” threshold for excluding transwomen from women’s services is high to the point of non existence. But the converse of that is that they’d need to acknowledge that the proportionate means of meeting the legitimate need of discriminating against a woman as Mermaids CEO was equally high, no? And what would that look like?
God, it would be utterly delicious if Susie took them to an ET with a discrimination claim where she argued that she’d been discriminated against for not being trans. Glorious, glorious stuff 
Equally interesting would be a non trans person not being employed in the new recruitment drive and taking them to a tribunal for unlawful discrimination on grounds of gender reassignment (that they hadn’t had).
Oh, what a tangled web!