Well, first I'm not sure Twitter can be considered 'broadcasting' or 'publishing'; it's communicating, but that may not be the same thing. Second, I think you have to show financial harm for a libel or defamation suit. I'm not a lawyer, so this is just my layman's pov. I think name calling goes on all the time on the internet, and I don't think there's a potential lawsuit behind every one. It's galling and ridiculous that they can get away with it, but then that's the very reasons they are doing it. In the end it's petty and foolish and no one with half a brain believes any of it anyway.
That's what I thought too, then I saw this - http://www.dailymail.co.uk/news/art...-libel-bill-target-successfully-sued-him.html I imagine this will soon be commonplace.