Actually, I'd like clarification how Restricted Boot helps a DRM system. AFAICS it will merely lull media companies into a false sense of security because they might think it actually secures the system while it only secures the boot process.
Take any software that implements DRM, run it in a VM and you can bypass anything. You will need to arrange to run the exploit every boot though.
I find most interesting the contrast:
Securing a PC against malware - good
Securing an platform against hacks on the DRM - bad
While these two situations are technically indistinguishable.