In Mumkey's Eliot Rodger review he is called out by Mumkey. He acts as though he had no control over Elliot going on a mass shooting, when that is a blatant lie. Before the shooting he heard about his son having many problems with depression and signs of extreme sexism. He never intervened or tried to help Eliot, which is what caused the massacre to happen. Despite these factors Peter acts as though he's in innocent and couldn't do anything about this. Which is why Mumkey hates him.