What's to say Spock won't use his knowledge to subtly guide and influence aspects of the new universe for the better. Quietly, behind the scenes...
Excellent point.
No, it's not. Unless Spock Prime has god-like illusions. Think of the power he would have making those decisions on his own.
I was thinking, it wouldn't be illogical (no pun intended) for Spock Prime to go to Starfleet and just start telling them everything he knows about his timeline. The universe has already been altered in such a fundamental way that there's no reason to try and avoid it.
What I'm wondering is why Spock, who used the "slingshot-around-the-sun" maneuver to go back in time and save Earth in ST:IV, doesn't do the same thing to save Vulcan?
Our heroes in TVH were trying to prevent something from happening, not change something that already happened. A subtle, but important difference.