If the reason is unknown to you, then why do you keep bringing it up with the not so subtle and completely libelous implication that he was in Seattle for a drug deal?
It doesn't matter. I mean, literally, it doesn't matter.
If the groupie knew anything about Seattle/King County, he would know that drug enforcement has been de-emphasized. It's not a police priority anymore, the local prosecutors don't prosecute it. It was a decision well publicized, made at the top.
They didn't care if he had drugs or not...and wouldn't have bothered to pick any up, even if they'd seen them.
If he knew anything...