I know, I can actually speak a bit of spanish myself haha.
But what do you do when you speak to a person who doesn't identify as neither? How do you justify the use of either no binario or no binaria? You need a gender for that. And if you can't figure out a gender there probably is a common or more agreed upon version or? I thought in this case more people might just use 'no binaria' for everyone.
Someone else mentioned 'no binarie' so I guess there's another way out of this.