Of course biological sex is not a spectrum. But trans activists are trying to get transgenders to fit the binary of the opposite sex. They are still their birth sex, however they present as the opposite sex and wider society will identity them as such (if they pass). Would a gender dysphoric man whom passes as woman, had all the surgeries be socially accepted in the male bathrooms?

Perhaps 3rd gender is better terminology? How transgenders (or other identities) choose to distinguish themselves within the 3rd gender is up to them, not me. Non-binary can be a stepping stone towards coming out as transgender. Otherwise, many are just gender non-conforming men or women that don’t really care too much about pronouns (once you grow in the real world, not tumblr).