What's terrible is not that Hollywood judged Kazan by his politics. I think it is appropriate to judge people by their politics, since one's politics are a conscious choice and not a genetic fact of birth.
What's terrible is that the vile politics of Hollywood's powerful elite lead them to ostracize not those who support thuggery, tyranny, murder and genocide, but those who oppose these evils.
It is not polite to talk about the gulags, the mass murders, or even what happened to the Rosenbergs. Perhaps all this politeness is not such a good thing.
Leni Reifenstal made great movies. So did Elia Kazan.
Muhammed Ali was a sensational fighter.
Paul Robeson was a wonderful singer.
Adolph Hitler was the master of political theatre.
Both the Nazis and Soviets had world-class physicists, engineers, mathematicians.
Why can't I celebrate their talents...and judge their politics separately?
Their talents in their chosen fields are beyond dispute.
Politics always raises unanswerable questions.