The temporal prime directive is placed in much later than Spock (with the Federation's time-fleet, though I suppose we could consider it "in effect" anyway), is routinely ignored (ST IV), and allows meddling for the purpose of restoring the "preferred" timeline (which Nero's presence broke, so Spock would be correct in "fixing" that).
Speaking of which, the 27th century+ temporal fleet *should* have intervened here.
Of course anything with time-travel is inherently broken (the Borg could easily have won in ST:FC if they had traveled back in time and *then* traveled the distance to Earth.)
People are welcome to like, or even love this movie (I'll be buying it because I love most of the sets, the effects, and the casting): but let's not pretend that there's a logical consistency to the plot