Originally Posted by martok2112
Kirk in the original timeline was the youngest man ever to command a starship....right at 30. It's possible that in this timeline, Jimmy T. is close to the same age as Spock knew him in the Prime Time Line, so it would be understandable for Spock Prime to assume Kirk was captain.
Pretty much said what I was going to say... Spock Prime was captured and put on DV4 by Nero. Spock knew roughly what year it was and just assumed Kirk was already Captain when they met in the cave. Spock didn't take into account that Nero was tinkering with events, but that should have been obvious when Vulcan went BOOM!!!