The issue isn't identity.
The issue is using a charity for women's health needs to trojan horse your own agenda and ideology with which is directly against the interests of those very women you are supposed to be centring.
If you are erasing the word woman and using dehumanising language like uterus haver in order to 'further the cause' then your primary agenda isn't tackling Endometriosis. Precisely because you are centring yourself NOT women suffering from Endometriosis. Its a massive conflict of interest.
A man could do the same job and it wouldn't be controversial for this reason - provided they were centring women and not using the charity for their own separate interest.
Thats why its not comparible with a non-blind person working for a blind charity. It would be a problem if the non-blind person was also campaigning for companies to have to comply with less 'reasonable adjustment' obligations under law and then saying that blind people who don't agree with this are just greedy benefits cheats who aren't working hard enough to overcome their disability.
This person is using and abusing the health issue of women who face huge obstacles and institutionalised prejudices to further their own position for personal gain. Thats revolting. Its actively exploitative.
Its the forceteaming and its the use of women as a tool thats an issue. Not the fact this person is trans.
Once you see it, you can't unsee it either.