If I were trans, that portion of the guideline would be enough to nope me out of participating in GNU projects. The "as you understand them" parenthetical gives cover for transphobes to intentionally misgender trans people, since they can hide behind saying that they feel it's only appropriate to use these terms for the appropriate biological sex.
> gives cover for transphobes to intentionally misgender trans people
It also gives cover to people who prefer to always use gender neutral pronouns. If a transphobe is acting on their views on gender to bully people, I'd rather deal with them on a case-by-base basis, while being empathetic to everyone else who might have meant to harm.
BTW, I've met RMS in person a few years ago, and exchange emails with him every once in a while. I've found him to be very fun, and not hard to deal with if you're used to hanging out with neurodivergent people.
I am no longer part of most of those communities, for both related and unrelated reasons.
Stallman is an extremely stubborn language hyper-pedantic with some fairly unconventional views and usages on any issue, not just this one. And he has 20 years of documented support for trans people. So with that context in mind, I think it makes sense to take it in good faith.
To say I find his position on this peculiar would be an understatement. But I find that on many of Stallman's positions on similar topics wrt. language. Either way, I'm reasonably confident it's not intended as a cover for transphobic bullying or the like, even though it may appear like that at a glance.