You have it backwards. Ideological conformity these days is enforced by creating the illusion that everyone around you is ideologically conforming.

The question is: is there a defense against this?

Your answer currently is there is no defense because creating an illusion of unanimous ideological conformity counts as an exchange of ideas and that exchange must not be hindered.

The debate is over whether the right to conduct Sybil attacks is more precious than the right to freedom of thought. The question is vastly harder than many people in this thread seem to believe.

My personal take is that the right to freedom of thought is more fundamental and that the value of freedom of speech is via its support for freedom of thought.