No one is endorsing it or fanning it in the McCain campaign either.
For once, use logic. A couple of nutballs in a crowd of thousands tells me that McCain is not exactly a major inciter of riots and crazed behavior. Crowds aren't running out of his rallies and burning cars, or even soaping windows.
The meme stinks. Give it up. I could pull that many looneys out of the audience of a symphony concert.