I fell like so much people in this post just don't get it. We are not talking about biological genders but about how a person feels. And no, you cannot say something about how people feel.
In other hand and answering to the post, in Spanish we have a problem about this topic. You see I have a genderfluid friend and I talked about this with this one.
In spanish we have three genders, just like in any romance language: male, female, and neutral. The thing is the male and the neutral are mostly the same.
I'll illustrate it with examples: If a want to talk about a male alumn, i'd say "alumno", and if it's a female alumn, i'd say "alumna".
As you can see, the las sufix, the vocal "o " or "a" stands for the genere. The thing is that if I'm going to talk about multiple alumns of both generes, I'd still say "alumnos", and the same if they are enterly male alumns, but I'd say "alumnas" if they are all female.
What I wanna say is my friend claims that this plural is not really non-binary (or neutral) because is just the same as the male one. My friend said (as many people try to), it's better to use "elle", that doesn't really exists in this lenguage. So that way, we should say "alumnes". I don't feel like it's really necessary since we already have a neutral gender, but the problem is most of people asume that it's male.
I don't know, maybe it's a question of how the sintax is learnt in the school, and maybe it has to be teached in other way in order to use it and understand it in the proper way.
Or at least that's what I think about it. But I still feel like they have more right to decide how to call them, even if we share the same language. In some way, this topic pisses me off.