MIchael Moore can threaten to sue all he wants but no civil judgment against anyone is going to change the reality that everything in this movie is a bald-faced lie. Now that's just all there is to it and he needs to learn to accept that he is simply not entitled to his own set of "facts."
Someone with time and money should take Moore up on his threat. It would be gratifying to see him have to defend the "facts" in his movie in a court of law. But, of course, like everything he does, the threat is just bluster. He'd never give his critics the chance to evicerate him like that.