McCarthyism was the Second Red Scare philosophy of "everything to the left of hunting the homeless for sport is communism and communism is the most dangerous thing in the history of the world" taught by senator Joe McCarthy and other closet fascists.
It was used as an excuse to hunt down and blacklist anyone they didn't like, whether they were left wing, Jewish, worked in Hollywood or, sweet merciful Anglo Saxon God more than one of the above.
The irony of him invoking that while unfairly punishing me for not following the local groupthink isn't lost on me, though I'm sure it is on him 😄