Blind speculation: I wonder if this is in some way related to DRM getting broken at a firmware level, leading to a choice being made between "users complain that they can't watch netflix" and "users complain that they can't install custom ROMs".
From the article:
Any subsequent attempt to install older firmware results in a permanent "hard brick" - the device becomes unusable
This implies that not only does an older custom ROM not work, but neither does attempting to recover by installing a newer ROM.