No need to give it back. Use it to promote your agenda (in Paul's case), not their agenda. There's a reason why Black donated to Paul: Publicity. There's a reason why this story isn't everywhere in the MSM, just beaten to death by haters of Paul in the blogs and Internet: It's intellectually dishonest.
I think it's because Paul can't afford to offend his base: neo-Nazis and Stormfronters.
Where is Fred/Romney/Rudy/Huckabee getting their money from? Corporate trans-nationalists, globalists, La Raza open borderists. Maybe some individual white supremacists donated to them too, who knows? Like I said, all of Paul's money comes from individuals. Making a big stink out of $500 from the $13 million so far that Paul has raised this year, that's straight out of the liberal textbook, which is what FReepers usually resort only when Dr. Paul is the topic.
If it’s only $500, why not just give it back or donate it to some Jewish charity or something?
Either Paul endorses Black’s anti-Semitism or he is just an inept politician. He could use this as his Sister Souljah moment but he chooses not to for some reason. It simply reinforces the quixotic nature of his candidacy and does nothing to dispel the notion that his supporters are Nazis and 9/11 Truthers.