Fortunately you're wrong, and the Supreme Court already addressed this. Freedom of speech doesn't mean you're free to say anything you want at any time, and it never has.

>As the Supreme Court held in Brandenburg v. Ohio (1969), the government may forbid “incitement”—speech “directed at inciting or producing imminent lawless action” and “likely to incite or produce such action” (such as a speech to a mob urging it to attack a nearby building). But speech urging action at some unspecified future time may not be forbidden.