Thing is. Nonbinary must be allowed to mean literally anything in the way it currently is defined.
I am a man, I identity as a man. However, if I were to Identify as Nonbinary, that would need to pass - I might internally and externally be male, but if I say I don’t identify with being male - it’s sexist to deny me the right to identify that way - because identifying that way is not tied to a specific thing you do.