He is intelligent. You don't go to Stanford if you're dumb. However he lets his emotions get the best of him. That doesn't mean that he is not intelligent.
Intelligent people don't act like that. He may have gotten good grades and gone to Stanford (which is a phenomenal school), but he's not a smart man. He's a fool. End of story. There are high school dropouts smarter than Sherman when it comes to how to act.