Revisiting "incorrect predictions" is a great way to learn about the error's in one's thinking and grow as a person. If your way of dealing with incorrect predictions is to pretend they never happened, then that learning can't happen. He doesn't have "meticulous, years-long grudges" against anyone who has made a bad prediction and learned from it. He does do it to people who refuse to admit they've ever made a mistake (eg the Bloomberg guy) or people who purposely make mistakes to pump and dump Apple's stock (Trip Chowdhry). To me that's fair game.