Hoffa’s vulgar rhetoric at the event — and the White House non-reaction to it — may expose the Democrats as gross hypocrites, but Obama’s appearance in Detroit raises more serious questions: Why should people vote to re-elect a man who is so plainly the political tool of the Big Labor goons who drove GM and Chrysler off the cliff in the first place? And why should people in the Great Lakes/Rust Belt region vote to empower a lame duck Obama agenda on the environment and energy calculated to kill jobs there?