I think that stupid comments from a drunken Australian is far from the Jews' biggest problem right now. This kind of crap barely deserves press coverage.
Mel was born in the United States and grew up in Australia and got his film career started there. He became a big movie star some 25 years ago and I suspect he moved to the LA area around then. I am not sure if he has dual citizenship but I would be surprised if doesn't consider himself American.