But liberals don't believe in free speech or in the First Amendment, we already know that.
Wrong.
It's a matter of law that speech which is not protected:
*libel
*slander
*fraud
*incitement to riot
*incitement of mayhem (yelling "FIRE" in a crowded theatre).
The film fits the fraud, riot and mayhem descriptions; because it has been claimed to be a history of Mohammed, it's a fraud, and because it's fraudulent history was intended to incite both riot and mayhem.