: That makes enough sense to me, I guess. It'd kind of make sense that if you
: were in the control room you'd be protected so that if you're on Halo when
: you fire it you aren't killing yourself. It just seems like a colossal
: mistake on the Forerunner's part to leave Flood behind at all after all
: the losses they went through, especially when they can be easily set
: loose(Installation 04) or escape(Installation 05). I think the Ark was
: meant to keep species around as the rings fired and reseed the galaxy..

: Another thing I've been wondering is why humans can activate Halo but
: Covenant can't? The rings didn't seem to be designed at a time when the
: Forerunner had much love for humanity, except for the Librarian who I
: doubt had much control over the details of how Halo worked.

: I hope it's not sounding like I'm trying to knock Halo, Bungie or 343, I love
: the series.

Humanity was basically set up as the inheritors of the Forerunner's legacy. That wasn't a fate everyone liked (Didact) but it's one that came to pass via the IsoDidact and Librarian. The recent Catalog posts on Waypoint suggest that only certain humans actually can act as Reclaimers, which implies the mechanism is via the genetic encoding the Librarian futzed with in humans.

Keeping the Flood in stasis was a gamble, but the Halos can not only nuke stuff not in containment, they can vent and destroy parts of themselves or even the whole ring if necessary to stop the spread of the Flood. Considering the Flood came from outside the galaxy the Forerunners decided better to keep some around for study and possibly find a solution rather than kill it all and be back to square one if the Flood returned.