I would say it's more to keep some weight on the rear wheel and prevent a low-side crash. When the bike is slowing down the weight shifts to the front, whether through friction braking or engine braking. If you are already at the correct speed, lightly accelerating helps bring you through the corner with more even weight on the wheels. Incidentally, race car drivers do the same thing, except when drifting, but you almost never see intentional drifting in road racing.