So here's the play.
And here's the AHL rulebook.
83.4 Disallowed Goal – If the puck is shot on goal during a delayed offside, the play shall be allowed to continue under the normal clearing-the-zone rules. Should the puck, as a result of this shot, enter the defending team’s goal, either directly or off the goalkeeper, a player or an official on the ice, the goal shall be disallowed as the original shot was off-side. The fact that the attacking team may have cleared the zone prior to the puck entering the goal has no bearing on this ruling. The face-off will be conducted at the face-off spot in the zone closest to the point of origin of the shot that gives the offending team the least amount of territorial advantagewa. The only way an attacking team can score a goal on a delayed offside situation is if the defending team shoots or puts the puck into their
own net without action or contact by the offending team. Other than in situations involving a delayed off-side and the puck being shot on goal, no goal can be disallowed after the fact for an offside violation, except for the human factor involved in blowing the whistle.
The bolded part is the key for me in saying that the goal shouldn't have counted but it also doesn't say anything in the rules about the puck hitting a stanchion and bouncing into an open net. I suppose it doesn't have to but they may have to add that to the rule book next year after this ending.