Prior to Tom Morello ‘s Defend Minnesota concert on Jan. 30 in Minneapolis, rumors swirled about possible surprise guest performers. And for about 90 seconds, when the guitarist walked onstage and kicked into Rage Against the Machine ‘s “Killing in the Name,” letting the intro echo through the hall as the fans erupted, there was genuine hope that a miracle might take place. But then Morello held his hand to his ear and instructed the audience to sing in place of someone who, yet again, was in