JeffH nailed it, I agree to the point of not needing to add anything to his comments.
As for Will Geer I really liked him in The Waltons too. As for the whole black list thing I've always had mixed feelings, on one hand I never like government power (the less the better) and McCarthy had a mean spirited feel about him. On the other hand Communism (responsible for the murder of over 100,000,000 people and tens and tens of million other deaths in wars around the world) was a grave threat to our free way of life and there was substantial subversive elements in the media that were communist agents, spies and/or propagators of propaganda. Hollywood really did need to be cleaned up, it was handled wrong (as usual) but the threat was real. I don't know what Geer did in all this or what happened to him during the hearings.