Actually, I didn't find the joke offensive. I thought it was ironic.
It's point is that ethnicity can sometimes contain intolerance.
I believe that was the point. People tend toward tribalism and support of their own. This is a double-edged sword. The joke could have been about any ethnic people and it wouldn't have made any difference.

I am proud of my Jewish heritage but at the same time recognize that cultural prejudices exist and don't need to be sweeped under the carpet.

At the same time, I think it's important that any ethnic group gets a chance to laugh at themselves once in a while as long as it's not vicious. I think that this joke did not cross that line.

Just my view.

Frank