In Star Trek: Countdown comic series, Spock failed to create Red Matter on time (before the Romulan Empire got destroyed by a Hobus supernova).
Despite Nero's excuses, Spock was a good guy. He accepted Romulus as his home (according to comics). Even Picard and Data (captain of the USS Enterprise of that time) were supporting him to save the Romulan Empire. Why didn't he save the Romulan Empire by going back in time?
When it comes to time travel, Federation had experience with it. Kirk traveled in time by the slingshot effect a number of times (ST: Voyage Home and ST:TOS). Picard also returned back to future by reverse tachyon pulse (ST: First Contact). So, they were certainly be able to time travel.