The movie never suggests that he does. In fact, during the movie it makes it explicitly known that his ship stands apart from the Romulan Empire.
Also, we have to keep the destruction of Vulcan in perspective. True, it's a major blow to the Federation to lose one of its founding worlds, but it's far from a crippling one. At the time of the movie, the Federation was comprised of 120 worlds and 700 colonies. The ships destroyed by Nero near Vulcan wasn't an entire fleet, just the ships that happened to be nearest to Vulcan, and what, then there was only like fifteen that were destroyed? The Klingons lost more ships when Nero destroyed their prison world.
The Federation's main fleet remains intact, and there are still 119 other planets that it can draw on for troops, ships and other materials. They're weaker than before Nero appeared, yes, but they're far from a sitting duck.