If "_key2" is an public key embedded within Windows, then presumably there exists one or more holders of the private key somewhere - what exactly are they able to do with this key?

I've seen a lot of concern about "_key2" and "_NSAKEY" being expressed over the years, but scant technical detail.

Putting some sort of security backdoor or snooping feature into your software (likely by government order) is pretty different from 'M$ gives 0days to spy agencies and delays fixing them'. _NSAKEY, whatever it is, doesn't resemble the situation the original article is describing.