The question is how to talk to and about other members of the community.
Calling other people by their preferred names is a basic norm that goes beyond gender.
Gender expression is rarely relevant in the context of software development, but gendered language is common enough in English to make the issue of gender identity unavoidable. You can require speakers to respect others' preferences, mandate gender-neutral language, or allow speakers to refer to others however they like.
Is it not possible to refer to someone by the name and pronouns they refer to themselves by not because you believe in the validity of transgenderism, but because that has simply always been the social convention? Gender identity needs to play no part in it, even if gendered language is being used. The outcome in the software should be the same whether the developer who claims to be a woman is really a man or vice versa.
Someone who isn't satisfied with that but rather requires full intellectual submission to their ideology is just as disruptive on a software mailing list as those who go out their way to "root out the trannies".
Calling other people by their preferred names is a basic norm that goes beyond gender.
Gender expression is rarely relevant in the context of software development, but gendered language is common enough in English to make the issue of gender identity unavoidable. You can require speakers to respect others' preferences, mandate gender-neutral language, or allow speakers to refer to others however they like.