Perhaps he isn't trying to get home because he knows it is no longer there? He's not the one that
It's Nu-Spock who says this:
The contrary, Nero's very presence has altered the flow of history, beginning with the attack on the USS Kelvin, culminating in the events of today, thereby creating an entire new chain of incidents, that cannot be anticipated by either party.
An alternate reality.
Whatever our lives might have been, if the time continuum was disrupted...our destinies have changed.
Old-Spock doesn't say anything on the matter one way or the other. Spock may have decided to stay to help the Vulcan survivors simply because he doesn't have anywhere else to go. If he had the chance you'd think he'd be concerned about the survivors of Romulus who don't have the Federation backing them up.
Well, the comic book tie-in for the movie (Countdown) showed that the 24th century as we know it still existed after Spock and Nero disappeared. I think it is safe to say the the 24th century he knew still existed. Plus, old Spock knows about alternate universes from past experiences.