Cannot be more of a death trap than a Renault Twizzy which I see quite often around the city, or any motorcycle for that matter.
As long as they don't market it as a normal car, I don't see why it shouldn't be allowed.
Are you referring to it as a death trap based on it's crash test performance or solely on the looks?
It is possible to make a safe lightweight car. DLR is proving it with their research.