I think they make helmets like that too, but the article mentions that this thing is totally passive: No solar panel or batteries. I'd definitely rather have a SNELL rated full face helmet (this one isn't SNELL approved btw) with a flip-down insert or like you're describing with the solar power/on-off ability.
You really can make it illegal if there's the political will to do so, but it's a hot potato, so the likelihood of of the practice being formally reigned in is unlikely. You make fruit of the poisonous tree absolute and create laws that make illegal search or seizure kill investigations without the possibility of future charges for a given criminal act.
Obviously that would also have practical drawbacks as well, but it is certainly legally possible.