Politically shrewd for each of the 3 primary governments involved, removes the issue from the agenda. I'd say its zero-sum outcome for any player: as many people will be angry as happy he's freed. the point being it can't be weaponised as easily as having him in the cell. Sweden may differ of course. I don't think either of the 3 primaries care what Sweden thinks.
Sweden does as the US tells.
Edit: Your down votes do not change reality. More important countries than Sweden have been satellites, such as East and West Germany.