This is where it ends up! The anti-trans people who are like: "What is 'trans', really? How do you know? Can you prove it? Why should I believe in it?" usually have arguments like: "Are feelings real? They might be delusions! Or they might change, and if they do, we ought never to have affirmed them in the first place!" etc. Logically that ends up as discarding all sexualities too: the identity labels, certainly, and probably also the associated relationships and behaviors. The queer person can't simply respond, "It's important to me to do what I want with my life," as the response will be, "What's 'important,' really? How do you know what's important to you? Can you prove it? If not, why should I believe anything you say?" etc.