I think MusicBrainz is about maintaining a database with useful and relevant information.
We don’t need to know the shoe size of artists. We don’t need to know if an artist had a single parent. We don’t need to know his/her sexual preference. We don’t need to know about criminal records. We don’t need to know about physical or mental handicaps.
While a lot of such information surely can be interesting and sometimes valuable, I don’t think for each of such elements MusicBrainz should have some standardized mechanism put in place.
They can all be added as side notes or additional information if interesting and somehow relevant.
But I wouldn’t argue that any of them is of enough importance and relevance to put effort in trying to categorize them.
Male or female is obviously useful.
Just look at a current project going on at MB to promote and improve information on female composers.
That would be impossible without a simple male/female switch.
I am still not sure I understand how your ideas about this matter would turn out to work in practical reality here.
But to wildly paraphrase something you said earlier, I am willing to learn about ‘new and additional rights for others’ that don’t take away existing ‘rights’ that the vast majority of people are content with and have agreed on.
Could you give some specific designations for non-binary genders that you propose to use on MusicBrainz, or else the most common ones that we could expect to encounter?
And could you give some explanation for each of them what the added value would be for having those categorized and available?