You could tell Callum almost lost his cool several times hearing it, but it was indeed quite the feat that Carl kept his cool.

As for your wider point: As if to prove that the Left only learns when it affects them personally, there was that part at the end where they pointed out Kentler only realized he may have made a mistake because the boy he had been abusing committed suicide when he became an adult. And it was only at that point that he read other works and realized "You know, maybe doing these sort of things was a bad idea." Still never disavowed his work though. Because what Communist would ever disavow their own work?