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You say: "But let's grant your premise, that Obama's not a "uniter." The question then becomes whether McCain and Clinton are more unifying, and then the question becomes, unifying to what end?"
The question all along has been whether McCain and Clinton are more (or less) unifying, because that's how Obama framed the terms of debate at the outset (that and 'hope' and 'change'). This in itself was an entirely false premise - something more in the nature of a crusade rather than a political campaign meant to deal with concrete issues, but initially at least, Obama got away with it. And that's where all the trouble started.
BTW, I'm not clear as to why you chose not to read the NoQuarter essay. It expresses far more eloquently and comprehensively than I am able to, the deep unease and distrust which Obama has inspired in so many.