In my experience many people (unfortunately) generally feel free to disparage non-gender-binary concepts on internet communities
Not that that's necessarily wrong - I'm definitely sympathetic to the argument that the personal is political. But that argument would justify more technical communities taking political stances, not fewer.
If, however, some community members wish to do that, they open to others the option to speak their minds on the topic, including stating that such an action ought not to be taken because no such gender exists. Contrast this with how most "codes of conduct" are written: they would permit community members to speak in favor of such a decision but not against it, as doing so would be "hateful", "bigoted", or "exclusionary".