Blind linesman who didn't see the puck was on the blueline when Duchene was 3 feet inside? I think the ref assumed it was on his sick instead of actually watching the puck itself.
Horribly bad call.
Considering the crap defense on both sides...it's fitting. Both teams suck in their own zone, so why can't the linesman suck too?
Edit: Radek just said it's likely a bad rule interpretation. If a defender carries the puck into his own zone, offsides should then be ignored, and the puck deflected into the zone off a Nashville defender. The defender never had possession thus that rule should not have been in play.