I highly suspect the word "should" was used not in legal sense, but in ethical one. You're right about GPLv2 — vendors are not legally forced to provide any wa

I highly suspect the word "should" was used not in legal sense, but in ethical one. You're right about GPLv2 — vendors are not legally forced to provide any way to load modified binaries (that's the primary reasoning to license software under GPLv3). Yet, there is a belief that every hardware manufacturer should do so to respect the customers freedom to tinker with the device, especially after the support from vendor is gone.