First of all, make sure B&N is violating the GPL. GPLv2 does not require them to make it possible to flash a new OS into the device and boot off it. As long as you can compile the sources into an executable that can possibly run, they are compliant.
I too would like Linux to be licensed under GPLv3, but a lot of companies wouldn't. I seriously doubt my TV manufacturer would be OK with me running my own code on it. Or my cable box.
Samsung use (used?) Linux as the base OS for a large number of their TVs so of course replacement firmware projects sprang up (e.g. SamyGo [1]). The project added additional functionality to their TVs like playing movies from a USB stick - features that Samsung had restricted to their higher-end TVs.
Within a few months Samsung had released an ‘official’ firmware upgrade that removed the ability to load unofficial (unsigned I guess?) updates.
I too would like Linux to be licensed under GPLv3, but a lot of companies wouldn't. I seriously doubt my TV manufacturer would be OK with me running my own code on it. Or my cable box.