My car also disables the start/stop system when I unlatch my driver's seatbelt. The engine does start by turning the key, though.
I think the logic is that if the driver left the car, there should be no danger of the engine starting without a driver, in case someone or something accidentally pressed the clutch.
I think the logic is that if the driver left the car, there should be no danger of the engine starting without a driver, in case someone or something accidentally pressed the clutch.