Not unless they weren't just banned or suspended, but also had their real name posted by JimRob or an AM, along with an explanation for their banning that included outright libelous statements. (And we all know that no AM or JimRob would ever do something that stupid.) Online communities have been around for well over two decades now, and nobody has ever successfully sued a privately-run community over a banishment. I think only a couple of people have ever even tried, and they lost big time.