Yes all the tweets quoted in the article were obnoxious and leveraged stereotypes but I don't think people should be flogged for being like that.
I remember all the obnoxious Polish jokes growing up. They were terrible. But I don't agree that they should be censored. Demanding this mind of self censorship is a sign that a society is fragile rather than robust. A robust society can take the jokes.
It's like with friendships. With good friends you can nettle them; say terrible things and we know that's it's all in good fun, a ritual of sorts. With so so friends you don't make bad jokes because the friendship is too fragile. It's a sign of an immature or fragile society when bad jokes upset the cart.
Edit. An irony is that many of the people calling offense don't realize their own transgression in becoming part of a self-righteous mob meting out punishment at the speed of thought.