If you want half the power, you have to be willing to shoulder the same responsibilities.
Pardon?
Women didn't opt out of serving in wars, it was a decision made by men who informed women of their executive decision. It's not something women have ever been consulted about, or that the male sex considered that females should have a voice in. Female service personnel world wide have fought for decades to be allowed to do more than typing. That 'shoulder the same responsibilities' bit sounds a bit paternalistic to say the least. Females could well point out many responsibilities that males have never shouldered at all.
And the point is: if you go with identitarianism a la Biden, men is a mixed sex group, and anyone not wanting to be a man and perform manly stereotypes and roles has other opportunities.
Or alternatively, it has to be admitted that sex exists, everyone knows it and it can be used when it's convenient to male agenda. Which makes it very difficult to explain why people of the female sex can't name themselves or group themselves by sex.
Other than that it inconveniences the male sex, who have the power to make decisions and inform the female sex of their executive decision, while not consulting them or seeing them as having any voice or stake in the matter.
Which would make it overt and appalling sexist behaviour on the part of males. Which is kind of getting to the definition of male supremacism.