Calling people "useful idiots" is pithy?

In this context, I would call it pithy sure. It's concise and direct. He's not explaining further.

He clearly isn't calling the other categories he listed (the " Retired, Unemployed, Unemployable") useful idiots, that's why he listed "useful idiots" separately. I don't know to whom he is referring as useful idiots but I don't think it's immoral in itself to use the term "useful idiot."