But to address your point - having Nimoy play an older nuSpock would be confusing despite any kind of magical writing, because Prime Spock has been cemented as a (recurring) character in the nuUniverse.
I really don't understand what would be confusing? Audiences weren't confused when Nimoy played Mirror Spock and they weren't confused when other actors played Spock in Star Trek III.
You tend to underestimate people.