Archduke Eduard Habsburg of Austria is the nicest guy on Twitter. He never argues, no matter the bait—and there are boatloads of chum in the water, but he never takes it. When Queen Elizabeth died, he Tweeted a sympathetic note. Someone called him an “inbred moron.” He said something nice about the Hungarian freedom fighters of 1956. He got jokes along the theme of “inbred, marry-your cousins…