NYCHRL isn't straightforward in its language, for sure; it's written for lawyers. It's also the legislation that applies in the jurisdiction in which the comment was made. In any case, seeing as RMS is, to all accounts, determinedly heterosexual, I'd say that it falls neatly into the category of "sexist remarks based on gender", the sixth bullet in that second document.
Maybe you think that's an unworthy bit of lawyerly ratiocination, but even so, consider that a comment like that would get anyone who made it fired from any tech company with an HR department and an employee base the size of that talk's audience, and for the same reason around which the GNU maintainers' statement revolves.
To your last point, I don't think it is unreasonable to hope for some positive impact out of all this, or I wouldn't have said anything even now. I'm not here to try to dogpile the guy; I'm here to talk about how, no matter from whom they originate, comments like this aren't "just jokes", that they aren't harmless, and that there's nothing honorable or worthwhile in defending them or the people who, as in this case, persist in making them past all reasonable expectation or effort of curtailment.
I feel like that's worth talking about, if for no other reason than because the man's been regarded as a hero by many, some of whom may really need to be told that there are some aspects of his behavior which are not acceptable, and which they cannot expect to get away with.
I'd prefer it if someone like that were to understand why this is the case, and agree that it should be. But I'll settle for someone like that getting the idea that, whatever he may think of this whole idea, he'd better learn to keep his mouth shut instead of saying things that hurt marginalized groups, or else expect to be made sorry.
Maybe that sounds harsh to you, I don't know. It sounds harsh to me. Being made fun of for being a woman, or gay, or a person of color, or Jewish, or trans, or disabled, or... - that's a hell of a lot harsher, and it normalizes and, as is amply exemplified in history both recent and otherwise, encourages behavior that's far harsher still - discrimination, exclusion, robberies, beatings, rapes, murders. That sort of behavior, I'm absolutely fine with being harsh in an effort to dissuade.
Nobody gets to choose to be - or not to be - a woman, or gay, or of color, or Jewish, or trans, or disabled, or part of any of the other axes of marginalization in our societies. Everyone, though, has the power to choose what they say. I want people to choose wisely. If their native empathy doesn't suffice them as cause to do so, I have no problem in principle or in practice with the fear of punishment taking its place.
That, after all, is the tool societies ultimately use to discourage behaviors they regard as unacceptable. What our societies find acceptable is changing. I understand that some people really don't care for that. But, again, facts don't care about their feelings. And when we have the US Supreme Court considering whether to explicitly exclude LGBTQ people from civil rights protections, and Germany's AfD frightening Jewish people into hiding their ethnicity - when those aren't even the worst examples you can find, just the first two that came off the top of my head - it's getting awfully late in the day to take a softly-softly approach.