From my perspective (as a person who is also queer and non-binary), few people are 100% straight or gay. If a straight person is occasionally attracted to someone of the “same” sex as theirs, that doesn’t automatically negate their heterosexual identity. So if the person they are attracted to is non-binary, but presents as — from the straight person’s perspective — the “opposite” sex to theirs, that attraction doesn’t mean the straight person should now automatically identify as queer.
I can understand that actually starting and sustaining a relationship with a non-binary person is different from simply being attracted to them though. Before my transition, I always preferred to date bi men over straight men. It wasn’t until I realized that I was not only not a woman, but non-binary as well, that I figured out why.