Women's chess is a protected category. On that basis, FIDE are stating that women who don't want to be women can opt out of that category if they so wish, but men who say they are women cannot opt into it.
I don't think that is correct. What FIDE is doing is taking away titles earned by people who are now trans men that they earned when they played as women.
In international chess there generally aren't any men's competitions. There are competitions that are restricted to women and competitions that have no sex or gender restriction.