I agree.
The context here is that it was originally published in a more leftist student type magazine. I don't think anyone who would have had a subscription to that magazine would have missed the joke. I understand why people would not want this published. But, like I said, it's a way to mock racism and show how ridiculous it is. The cartoonist now has a black wife (who is an Olympic gold medalist btw) and they both joke about race quite a bit. I believe it's their way of saying race doesn't matter and trying to disarm racial tensions.
Personally I also feel like evading certain jokes or topics victimizes people a second time.
@Osman usually has strong opinions about this, I wonder how he feels.