You have no idea how this ring works, do you? Why the Forerunners built it? Halo doesn't kill Flood, it kills their food. Humans, Covenant, whatever! We are all equally edible. The only way to stop the Flood is to starve them to death, and that's exactly what Halo is designed to do, wipe the galaxy clean of all sentient life! You don't believe me? Ask him!