As a general matter, individuals have extensive rights to engage in protest activity and that's particularly so when that protest comes in the form of speech. What individuals do not have the right to do is to engage in action that interferes with the legitimate activities of other people. For example, people are free to go to a movie set, for instance, that's in a public area and pass out fliers and engage in other forms of protest. They cannot, however, trespass on a private property studio, destroy property being used in the movie, nor could they engage in any other activity that interferes with the lawful activity of others. The Klan, like any other controversial group, has a right,under our constitution, to engage in peaceful speech.
Nobody has to listen to it, and everybody is free to either ignore it or condemn it.
It may well be that it is unconstitutional under the state constitution in Michigan as well. And the supreme court has held that the government has extensive authority to regulate the content of TV and radio broadcasting and pursuant to that authority, the government can and has limited the ability of broadcasters to broadcast certain language that may be offensive to many. Such as expletives. The ACLU, two years ago, successfully challenged a federal statute that attempted to make it a crime to put indecent material on the internet. In that case the supreme court held that the internet is like newspaper or other types of private communication that is subject to full First Amendment privileges.