Actually, the Logo requirements specify that you must be able to add your own keys:
> It shall be possible for a physically present user to use the Custom Mode firmware setup option to modify the contents of the Secure Boot signature databases and the PK.
The former claim is absolutely true, and I'm not happy about it. But that is surely the standard for all ARM devices out today, is it not? Locked bootloaders?
Anyway, the latter claim is purely conjecture. Why would they change convention once everyone has already implemented all this standard/custom mode stuff that they require for 8?
> It shall be possible for a physically present user to use the Custom Mode firmware setup option to modify the contents of the Secure Boot signature databases and the PK.