Racism?(throw the jew down the well?)
When a Jewish comedian sings about other Jews, in a satircal way, it's hardly racism.
No different than milo taking the piss out of gay culture....Hardly a homophobe.
Sacha Baron Cohen is himself a Jew who is likely not an anti-Semite nor a racist nor a homophobe. He used the Borat character to force people to confront their own biases in unconventional ways.