Re: IDW Star Trek Ongoing...
Elderly Spock in the Mirrored story certainly isn't from the MU. Aside from the obvious lack of goatee he talks about the Federation, and remembers the Terran Empire as being from an alternate universe he once encountered. But I really can't see how he or Nero can be from the Prime Universe, so they're likely from a different universe entirely which is similar to the Prime.
"Internet message boards aren't as funny today as they were ten years ago. I've stopped reading new posts." -The Simpsons 20th anniversary special.