The only time you might think his hand is off the wheel is when he is adjusting brake balance while covering the duct.
But the brake balance dial is on the wheel therefore his hand is still on the wheel.
Brake balance isn't a dial on the wheel - it's a physical lever.
it is possible to do it through a servo system, but as far as I am aware not many teams have gone down that route as a lever is less prone to failure.