Knowing about something in a general sense does not mean you are able to stop it, especially in this scenario (if it was a FF). As far as we know the NZ government is in league with the people that would have done a FF. How exactly was the US/Q supposed to stop something with NZ on the side of the attackers? From what I can see, Q/USA now stops the specific attacks they can... they also can warn us when they hear chatter or believe an attack is coming but Q/US don't know where. Remember the other side does have some competence.