Robogeek: Why doesn’t Spock Prime try (or even want) to fix/restore the timeline, and save Vulcan?”
BobOrci: Two reasons: The RED MATTER Device is destroyed, so even if he wanted to go back in time, he can’t.
Secondly, our story is not based on the linear timeline of Einstein’s General Theory of relativity upon which most movies about time travel are based (like say, BACK TO THE FUTURE, or TERMINATOR, both of which I LOVE). The idea of a fixable timeline has been a wonderful staple of sci-fi since the 50’s, but in reading about the most current thinking in theoretical physics regarding time travel (Quantum Mechanics), we learned about the speculative theories that suggest that if time travel is possible, then the act of time travel itself creates a new universe that exists in PARALLEL to the one left by the time traveler. This is the preferred theory these days because it resolves the GRANDFATHER PARADOX, which wonders how a time traveler who kills his own younger grandfather would logically then cease to exist, but then he’d never be around to time travel and kill his grandfather in the first place. Quantum Mechanically based theories resolve this paradox by arguing that the time
traveler, in killing his grandfather, would merely split a previously identical universe into a new one in which a man who is his grandfather in another universe is killed in the new one. The time traveler does not cease to exist, although he is no longer in his own original universe (where he is now missing). Or something.
To summarize above on the time travel issue, going back in time is the equivalent of stepping into a parallel universe, according to current speculations based on Quantum Mechanics.
Starfleet and Spock, basing their decisions on this theory, would see that their is NO SUCH THING as “rectifying” the situation in a MULTIVERSE.
… and finally, my ace in the hole, a TEMPORAL PRIME DIRECTIVE.