What is the "concrete meaning" of "non binary" gender, as opposed to the made up label, please.
I think I can offer a concrete meaning:
A "non-binary" person is someone who believes they have neither a male or female gender identity.
Now, by that definition, we're all non-binary. Unless the label has to be self-applied, as Discovereads seems to insist for some reason. But even if self-applied, we need to have a definition to know whether it applies, and that's one we could use.
(Although in true self-ID world, presumably someone who believes they have a male gender identity could also say they were non-binary?)
But there's a tighter definition we could also use:
A "non-binary" person is a gender ideology practitioner who believes they have neither a male or female gender identity.
That is possibly a more useful definition, as it gets to the core of what non-binary means in practice. A definition that includes everyone is not terribly useful, and it's that very specific minority of people that are being targetted in legislation.
But the important thing to note is that the thing that distinguishes them from the vast majority of population is then NOT the lack of male or female gender identity, but the belief in gender ideology.
And one of the core tenets of gender ideology is that "all non-believers have male or female gender identities, determined by their sex".