I don't agree at all. What about an energy company denying you connection to the grid because they don't like you? Or the telephone company doing the same? And what if these companies are monopolies in the area, or if there is only a handful of companies and they all make the same decision- perhaps out of fear of losing other customers to the competition?

Facebook is a de facto monopoly in the social networks space, and it's deciding to deny service to specific individuals based on their political opinions. It's not something I'm willing to shrug off as unimportant.

And I have to disagree with xkcd too on this one. Protecting the freedom of speech means setting limits to the freedom of others to harm you when they don't like what you say. People are free to disagree and switch channel/ unfollow/ stop buying a newspaper/ etc. But harassment and mobbing are a different matter.