User blog comment:Bluebeard2/Philosophical discussion concerning the nature of Necrons and Tyranids/@comment-2253300-20111018005329/@comment-2253300-20111018144701

Not if the Hive Mind determined that the Necrons and C'tan were threats to both its food and its survival. Then the Tyranids would go on the attack and seek to wipe out any threat to them.