My theory is simple.
The original jailbreak emulated USB hubs. Sony killed third party peripheral support, meaning the PS3 ignores the "fake hubs" when booting up...
...solution: use the USB ID codes of the Sony-made USB hub packaged with the Move kit. Presumably, the codes can be used to generate the same space needed to deliver the payload for the exploit.
I'd guess they didn't (perhaps couldn't) remove the actual exploit itself, and instead attacked the easiest thing to "eliminate" the problem. I'm not sure where the ciritical chunk of code lives - if the exploit is caused by code in the hypervisor, perhaps that's not updateable?
Working hard on UberCFW, incorporating NTFS, sub-free NetFlix and Blockbuster, PSN cheat system with built-in swearbot and MAC-spoofing, Adding MKV, RAM and BIK movie support, and Xbox360 emu*.
*not really. Get a life, newbs...
My YouTube channel: http://www.youtube.com/user/BenJeremy