The concert was suppose to promote drug treatment for addiction in the USSR.
That was a trend for a while "community service" because drug smugglers were just mis-guided youth who with love and tenderness would be reformed. Especially if they had connections.
Maybe, I would believe it, if it was an anti-drug show in the U.S., but why the USSR? They weren’t even an ally then. I don’t see a judge caring about international relations.