I can't be positive, but I'm pretty sure he's the Doobie Brother who tried to enlist in the Petaluma Police Department, back in the early 80s. The timing certainly adds up. Also, he did live semi-locally to Petaluma, on his horse ranch.

I say he tried to enlist. As the apocryphal tale goes, he made it pretty far through the hiring process, until it came time to talk about past drug use. As local legend goes, his response was, "I was a Doobie Brother, man. What do you think?"
And that was the end of his attempted career in law enforcement.