It's a violation of freedom to speech.
No, it isn't. It's freedom of association. Freedom of speech does not apply to private associations. If a private association has rules which say you're not allowed to say certain things, they are free to prevent you saying those things within that association, and they are also free to prevent you from associating with them if you violate their rules. By the same token, you are free to form your own association with its own rules, if you want to. But as long you're a member of
this association, you have to follow this association's rules. Okay?