Except it doesn’t. It’s not the body panels that are rusting. It’s the airborne iron particles (mostly) from brake rotors that land on the stainless steel and react with it causing rust but it’s actually just surface contamination and cleans up rather easily. This is in no way issue exclusive to the Cybertruck.
Fallout remover is a commonly used product among car detailers. It just doesn’t react like that on a painted surface.