That’s what Trumbo did in fact. Being blacklisted was a trifling inconvenience.
I have yet to encounter accounts of actors who were unfairly accused of having Communist sympathies.
The defenders of Lucille Ball admit that she was a card carrying member of the Communist Party but that she’d joined merely to please her Communist grandfather.
How would that fly if someone joined the KKK (as an adult, not merely dressed up by parents) for the same reasons?