Your pointing out a black man having a relationship with a white woman is a little strange...perhaps you have some sensitivity about mixing races...I don't remember too many freepers making that an issue....but to each his own when it comes to that....
Here's my take on that:
The Democrats may well be behind this, in my opinion. If that's the case, we know what the sort of doctrinaire Marxist Democrats that Obama is and surrounds himself with think of conservatives and Republicans. They believe that all conservatives are closet KKK members who are racist to the core and just itching to believe all sorts of horrible things about black men.
So they are using the old Southern Democrat hot button spectre of the black man seducing white women - because they think it will work to discourage the "KKK" Republicans.
Actually of course they are projecting their own Democratic fantasies onto others.
But I think that's what is going on here. I am old Southern to the core, back for generations, and that stuff is completely passe' now, as laughable as the histrionics in Birth of a Nation. Decent Southerners discarded those rumors and images long ago.
The wildness of the accusations is one of the things that sends up red flags for me. The whole scenario seems like a bad piece of fiction written for a Klan rally at Stone Mountain. In fact, it's almost identical to a poem that was read by an old lady at one of those rallies . . . . pretty well known incident that's in a couple of books.