If there is a specific target for an ability that is always not-in-play, it targets there implicitly.
Desecration of Graves targets Potter's Field in set-aside, because it targets Potter's Field specifically, which goes to set-aside.
Prince of the Air targets Chamber of Angels in set-aside, because it targets Chamber of Angels specifically, which goes to set-aside.
The best example of this is actually Falling Away:
"Select any Redeemed Soul and return card to your Land of Bondage. Character is treated as a Lost Soul. Subtract the rescue from appropriate player's current score. "
Nowhere in there does it explicitly state that it targets cards outside of play, but it implicitly states it by targeting Redeemed Souls specifically, which can only be held in Land of Redemption. Without this implicit default targeting, not even that card works, hence the ruling.
So, when there is an implicit targeting location based on the specific target, which is always out of play, the card that does the targeting can still target there without being explicit on the out of play area.
