If it were just indifference, like if a "non-binary" person didn't want to emphasize their gender or certain role, but "non-binary" people go way beyond that in they refuse to be classified by a gender at all, believing they are a 3rd distinct gender, neither male nor female. If it were just merely indifference or want not to be limited by gender roles, that would a more individualistic worldview rather than coercing others to adopt their worldview.