I still have no idea what his personal motivations are.
At this point, he has to know rationally that a return to his previous form is not in the cards.
Is he worried about his legacy? I don't see how. He's been below replacement value on this contract so far, and his glory days seem like decades ago now. If this is it, I don't see how playing two more seasons of negative-WAR baseball is going to help his legacy any.
Is it the money? Again, surely not. He already has multi-generational wealth for his family... with sound investing, the Davis line will be set for centuries just from what he's already made. In addition, as others have mentioned, if he decided to call it quits, the Orioles would be very agreeable with a buyout at this point... if the team could save some percentage of the guaranteed money AND free up a roster spot from a negative production player, that would be a victory. So he wouldn't even be out all of the remaining money.
I just don't get what's driving him.