Freedom Cuts Both Ways
Freedom of speech doesn't just mean my right to say something that the government doesn't like, and to say it without retaliation either open or disguised. Freedom of speech means your right to hear what others have to say, and to form your own opinions free of interference from censors of either the governmental or the self-appointed kind.
When someone attempts to silence me by force, he's not just violating my rights. He's violating yours. That's why all of us need to stand together and fight it like hell when some asshole comes along and tries to silence me or any one of us. We as a race cannot make the decisions which will be necessary to our genetic survival if we allow anyone to take it upon themselves to decide who and what we can hear.