The reaction to Elia Kazan was pure blinkered idiocy on the part of those who sat down or didn’t applaud. There is no defense for it.
One other thing about Richard Wagner. I don’t think he can be compared to what Refeinstahl did. Though he was an anti semite to be sure, as far as I know he did not actively contribute to any Jewish pogroms or anything like that. He didn’t make music that progagandized people or had as it’s intent to brainwash people. That Hitler and the Nazis used his operas to champion racial superiority long after his death cannot be attributed to him.