It nods to the Lumpley Principle. A method is followed by which everyone reaches agreement about what happens in play. Perhaps it helps to picture GM as another player? Like all players, they get a say. Their say is not in contest with that of other players: it conspires with that of other players. The roles are asymmetrical, but equal.
- Someone asks "How can we be sure the dirt is in the safe?"
- Someone else says "The accountant accesses that safe every day to get the books."
- Someone else observes their known peccadillo.
- Some play happens. Some social interaction ability checks are called for.
- Finally at the safe, intents are known, consequences are understood, the location of the dirt is locked in.
It may be that some versions of S-N require only players and not GM to have a say. So for clarity that's not what's happening here. The truth is established playfully, following and within constraints of fiction, description, system... and of course, principles.
The fact of the matter isn't reached in one bound. It's not - from a cold start, someone at the table without a nod toward saying what follows and playing to find out, locks in what is in the safe. It's iterative. A big difference is that it's not locked in by the roll at the safe. Reaching that safe with an intent faithful to game-state (to retrieve the dirt) is a product of play. Players and DM all avoid fiat, by working together in good faith.