I really don't care if old Spock came from our universe, and there is evidence to suggest he didn't, for those who choose to believe it. But...
- Old Spock wouldn't necessarily have known what year he was in, and at 130+ years old, may not be able to tell a 25 year old from a 35 year old on sight. He does mention how many years in the future he is from, but that is after he initiates mind contact with Kirk.
-Simon Pegg is the oldest member of the new cast, ten years older than Pine.
-We don't know when Uhura and Sulu graduated from the academy or their ages. Nichols is only a year younger than Shatner IRL. Also, NuKirk enters the academy when he is 22 and completes it in 3 years, Uhura and Sulu were presumably several years younger than he was.
- We don't know how old Chekov was when he came on board the ship, just how old he was in season 2. NuChekov's age was fudged by 4 years, not ten (34-22=12, 25-17=8, 12-8=4)
-The Kelvin could very well take place 20 years before The Cage, given the different production values.