Again, the marriage of two people does not affect the marriages of everyone else.
If you want to leverage the very positive acceptance of gay marriage as a comparison, the appropriate analogy would be if in order to allow gay marriage, a new definition of marriage was based on the belief that all marriages going foward are considered same sex.
For all public purposes, state and social, any M/F couples would have to decide whether to describe themselves as M/M or F/F, and furthermore, not only is the label on their marraige changed, but because of that going forward the individuals concerned will be treated as actually gay for all public and social purposes.
There will be no space or language, legal or otherwise, for the public acceptance of straight marriage, and anyone complaining that while gay marriage is absolutely a fine and positive thing that adds to society in so many ways, it is not the universal experience of marriage, and other people's marriages are equally valid, will be told that while they can of course think about their own marriage in private however they want, recognising the truth of straight marriages publically is unthinkable because will erase the reality of gay people and the existence of gay marriages.
That is, of course, ridiculous. It is a million miles away from the real story of gapy marriage, so far away as to be laughable. Noone ever even considered it for one hot second.
And yet this is exactly what you are doing to women (and men) when you insist that including (karyotypically) male people in the social definition of women, or (karyotypically) female people in the social definition of men, is not a redefinition of what it is to be a woman or a man because we can still think about ourselves however we want in the privacy of our own heads, we just can't expect society to acknowledge and respect it any more.