If your foot is on the brake, the clutch will be disengaged, just like having you foot on the clutch in a manual car.
Cars with electronic handbrakes and/or Auto Hold will keep the brakes applied when the brake pedal is released, therefore also keep the clutch disengaged, so there is no mechanical reason why you shouldn't leave it in D or S.
As I've often said, it's good practice to not dazzle the driver behind with brake lights of too long, so in a Mk6, selecting Neutral and applying the handbrake is the courteous thing to do.