It was all just a lark. Didn't mean anything. Childhood banter. Ok. The child begets the man. As someone on the receiving end of similar jibes and japes I don't consider it's exposure desperate. Still it all depends on your pov. I suppose. There are children right now who are committing suicide because of Internet bullying (and worse).
I said some stupid things at school but I don't recall ever saying Hitler was right. Send Jews to the gas chamber. Today's Guardian. (Can't link for some reason)
Still one man's banter is another man's ...what? Reason to develop depression, turn to violence as a response....it's OK all just joshing fun.
However I wish the press would concentrate on a more rigorous investigation of his Russian links as I think the exposure of those would do him significantly more damage. He probably welcomes the distraction of his exposure as a Racist, it does play well with a large part of his supporters if the usual places on the web are to be believed.