Larry King may be from the stone age, but that doesn't mean he knows much about actually being stoned. Unlike dope fan Willie Nelson, who hits the weed more often than Larry plays the ponies.
In fact, there's apparently very little Wille doesn't do stoned (he made the decision to be in Beerfest, which must prove something), including sitting across the desk—on 4/20, no less—from Larry, who'd probably be more at ease interviewing drunken bootleggers. That prohibition was a hoot, eh bub!
When King reacts to Willie's placid admission that he has that sweet mary jane coursing through his veins live in the studio, well, some production assistant no doubt had the defibrillator ready.
Pot? Edward R. Murrow didn't have to deal with this!