For more than a decade now, Megadeth frontman Dave Mustaine has been critical about politicians and distressed by the establishment. But even as the metal veteran lashed out at corruption, greed, and megalomania on songs like “The Threat Is Real,” “Post-American World,” and the title track of Megadeth’s 2016 album Dystopia, he has remained a firm believer in democracy — at least in theory. ...