Of course, what was really involved was money. War is good for business. Business had been great during WW2 and the newly created "Cold War" was just a way to keep business good. The Military Industrial Complex NEEDED Hollywood to demonize the Soviets. Otherwise, too many people were going to ask why we were being told to be so afraid of them, and few in the government had a really convincing answer for that question. So, in order to perpetuate the Cold War, those in Hollywood who might sympathize with the designated villains had to be removed; their ruined lives a small price to pay for unending access to the taxpayers' wallets.