As emphatically as I support the article's author's right to his opinion, and to express it, I stop short of agreeing with your position. We absolutely have the right to express any opinion, but speech is not absolutely free.
There's the cliché example of "Yelling 'Fire!' in a crowded theater". That's illegal, and with good reason. A more compelling case of legitimately restricted "speech", however, is incitement to violence. If you're actively encouraging people to commit violence on persons or property, that shit has to stop.