No, you don't understand. Facebook has a policy saying they won't disclose personal info, like what age you are.
You're 100% right. Sexual orientation, however, is not private and is publicly displayed - there is nothing to "disclose," the user discloses it to the whole internet voluntarily.
... but it is impossible to log in to most social networks without HTTPS
An age is called Dark not because the light fails to shine, but because people refuse to see it. -- James Michener, "Space"