How have his rights to "free speech" been violated?
In the first place, if you mean the speech protected by the First Amendment to the Constitution, read the amendment again. The first five words, "Congress shall make no law", means that the government cannot censor you. It doesn't apply to private citizens or corporations.
In the second place, who, exactly, is preventing him from speaking? Nobody is doing that. He says what he wants in his nightclub, in his Facebook posts and on his recordings.
Perhaps you think "free speech" means, "you can say what you want and not have to suffer any consequences." Sorry, but life doesn't work that way.