I'm talking about the Unified Extensible Firmware Interface Specification (version 2.1.3, somewhere around page 1450 or so), which is written irrespectively of ARM or x86.
Are you talking about ARM or x86?
Your question probably refers to the Open Enterprise article which cites a RTW of Windows Hardware Certification guidelines? This, if that is the final version of the document, and if manufacturers implement it, would at least lessen the evil somehow. Although disabling safe boot could temporarily work around the problem, it does not address the problem (nor is it a good workaround, it actually defeats the purpose). To remove the key, you still need a zero-key signed by Microsoft. Otherwise your motherboard is non-compliant.
Don't get me wrong, safe boot is a good thing, and it should be enabled. It's just that you should own the master key, since you're the owner. Heck, you paid for it.