Very good post that highlights many of the difficulties in attempting to solve the problem of governmental access to encrypted devices and encrypted communications.
I think that when technical novices, such as Cy Vance, attempt to solve this problem, and put forward their own ideas, it creates opportunities for discussions of real substance on the subject to take place.
Their solutions are considered by technical experts from all around the world, and the flaws in those solutions can be quickly identified and then openly discussed, often in considerable detail. Such discussions educate the technical and non-technical alike. In particular, many politicians that hold strong opinions on this subject are often not technical experts and it is through such discussions that their level of understanding on this subject can be improved.