My recollection is that Orton hadnt made a decision, then he had some sort of sidebar with Marone and ran into the locker room and cleared out his locker then announced he was retiring. Marone may not have announced yet but it appeared he had told Orton and Orton bailed.
That may be speculation but it makes perfect sense. Orton would not want to have to battle it out in the preseason with EJ again. He had a good thing going with Marone/Hackett but with a new coach maybe not so much. Take the money and run.
Although I guess it could have gone the other way too, as you suggest. Hadnt considered that angle.