He's sticking to his guns in a column at Politico:
I saw firsthand just how stupid pot made my older friends and scores of band members that I grew up with over a few decades. I played in bands from the time I was in sevehth grade and was probably more exposed to the use of illegal drugs than most middle-class Americans not writing for Rolling Stone.
I stayed away from pot specifically because of my experience with it. ...
Unlike alcohol, pot rarely makes you an angry stoner. Unlike coke, pot rarely makes you bankrupt. And unlike heroin, pot rarely makes you dead. Nope. In my three decades or so around a multitude of pot smokers, I have found that all too often, pot just makes you dumb.