So, since Polaris now has one Skeleton Key boss, that is to say, Omen Stribog, the Gold Key boss, I think it should be appropriate to give Polaris' bosses' Skeleton Keys in their loot drops, because once a new Skeleton Key boss gets added, all bosses should have their loot tables updated to accommodate that.
Here's the list of the bosses in Polaris that should have their loot tables updated to give them Skeleton Keys, notably Gold Skeleton Keys...