On the "Immigrants eat cats" thing. This is part of a long, particular history of using animals to other and vilify immigrants in the United States. Here's an 1871 cartoon describing anti-Chinese sentiment: "Coolie, Slave, Pauper, and Rat-Eater."
It’s also a long history of: “Ha ha. We kept these people so poor that they have to eat _______.” As in: We kept them so poor that they can’t afford ice cream, so we make fun of them for eating watermelon.
In the Australia of the 1950s similar assumptions were made about Chinese people
There was that whole "Chinese restaurants use stray cats for meat" thing that was a prevalent rumor back in the '70s.
An aside: The artist, while saying we're being unfair to Chinese immigrants, still manages to be unnecessarily racist against the Irish. I guess it shows we always need some group of people to hate.