Neither really.
Ma’at is an eternal concept, Zeus’ “nature”, but that’s not the right word as it implies it’s not a choice. It objectively exists in the same way gravity does.
Being good and truly abiding by the principles is actually the most logical thing one can do.
In one sense the Gods are like AI in that they would be completely predictable as they’ll always pick the most moral/just option. Humans due to our corruptible ignorant nature have this unpredictability on how we will act.
Good isn’t a feeling, it’s principle/attribute of Zeus similar to how his eternal knowledge is part of him. Ma’at was the same 13 billion years ago and will be the same 13 billion years from now. In a way it’s more permanent than the laws of the physical universe itself.