- last post: 01.01.0001 12:00 AM PDT
The Forerunners are not afraid of the Flood. They didn't put them on Halo so that they wouldn't get out. Remember what 343 GS said in the Library? "The Flood were placed on this installation so that they could be STUDIED.... I'm glad that some of them managed to survive and reproduce." The Forerunners like to study the Flood, they don't want them to die. In other words, they didn't want their experiment to get ruined.
Of course, they must have realized that if the Flood DID get loose, hell would break out. So they built a weapon into Halo just in case that ever happened.