I think your analogy is unfair. A standard car does make it harder but isn't being specifically modifed to make the action of police/TLA more difficult. A more appropriate analogy would probably be an armoured car or military humvee, possibly a tank. Should the public be allowed to buy a tank? It has got other uses than evading police but it makes the police's job much harder as they need to up their technology (bazookas and their own tanks) in order to handle criminal use of the tech in question.
Just to be clear I'm not commenting at all here on the question of limiting availability of crypto-lockers to the public.
Just to be clear I'm not commenting at all here on the question of limiting availability of crypto-lockers to the public.