It doesn't affect desktops in any way. It only applies to Win RT (ARM) systems, where the Secure Boot feature in UEFI can be bypassed to install other operating systems. One needs physical access to the device - it can't be done remotely.
UEFI systems have provision for a Secure Boot lock, which can be optionally implemented or switched off. Microsoft chose to implement it on its ARM-based devices. At the time (when Win 8.0 was released), some criticised Msft for not allowing Secure Boot to be switched off on Windows RT ARM tablets.
Now it seems it can. The way to do it was left in some debug code on a dev tool.
It's essentially no different to jail-breaking an iPhone or iPad, for example.
No "golden key" leak. And it doesn't affect encryption protection.