If he is open at all or has any self-awareness I would suggest he read
Leadership & Self-Deception. It may open his mind to what he's become blinded by. Otherwise, I would do like others have suggested and start finding something else.
Leadership and Self-Deception: Getting Out of the Box [The Arbinger Institute] on Amazon.com. *FREE* shipping on qualifying offers. Leadership and Self-Deception: Getting Out of the Box