What country grants any level of immunity to the bearer of a diplomatic passport simply for possessing such dip book?
Immunity is granted when an individual is accredited by a host nation, or in the weakest form of derivative immunity when declared on diplomatic note for accompanying a head of state or ministerial level official.
I'm unaware of anywhere that grants immunity for simply possessing a dip book. If you know, let me in on the secret so I can start changing my flight routing when working.