In fact both political correctness and political incorrectness have very little to do with free speech. They both tend to apply to subjects of permissible mainstream debate; which is to say; they apply to issues where divisiveness is encouraged anyway.
Free speech becomes an issue when you try to enter into public discussion things that challenge the real orthodoxies of power; such as; why do states have the right to murder people? Why do occupied people have no right to defend themselves? Why do businesses have impunity to profit from tyranny? Why is Capitalism treated as an unquestionable, sacred truth? Why can banks and corporations be bailed out, but people can’t be? Why aren’t food, shelter and clothing Human Rights? And so on and so forth.