however EBD is for aerodynamic purposes only,
exhausts are for exit of gases from the engine,
Exhaust blown diffuser which has a driver control (throttle) changing the flow of gases and the blown diffuser being for aerodynamic purposes only, it means the EBD is an aerodynamic device which can be controlled by the driver within the cockpit,,,, therefore technically illegal.
However you could go to the point where you say when a driver moves his head its affecting the aerodynamics of the car and is driver movement which makes the movement of the head like an f duct in the eyes of the rules, making a driver moving their head illegal
However hopefully the f1 teams wont go this far as we will just have little pedal gokarts driving round