When I was reading chapter 9, I completely missed that DOM can stand at either end of the problem - as the generator as well as the receiver of KDMs. It would be good to reference sectoin 5.2 Decrypting encrypted DCPs from Chapter 9, I think a good place would be after the sentence "They hide the private key deep inside the bowels of the projector (inside an integrated circuit) where no-one can read it."

I would add something like DCP-o-matic stores such keys in a file, see section 5.2 to learn how to share it with other so they can send you an encrypted DCP.