I think it’s worth noting that the bigger issue here might not be the drm, but the access Amazon has into your device. Regardless if you can download ‘another’ version of the book or not (that is something you can find out for yourself relatively quickly) there is no reason it should be considered ok for the company to insist that it can connect to a device you own and modify the contents of it. Even with ownership of the books being a topic, certainly there should be little questions of whether you own the device, and along with that being able to control access to it.

Surely there is something in the user agreement that states accessing the download functionality also grants Amazon permission to go in and claw back things they’ve uploaded to the device, but i think that should be at least half the argument. Restrict whatever they want up front, I’ve downloaded it to my device and they consider that a fair exchange for my money, but to then say they screwed up on their end so they’re taking it back (assumedly without giving up the money they made as part of the agreement) is where things should be breaking.