A couple of other items for consideration:
- Containment failed 300 years before Halo 2. How long was Gravemind around?
- If Flood spores escaped, what food source could they find, if any?
- It seems to me that Gravemind was indeed around for awhile before H2. After all, the Flood in H1 did not create a Gravemind even though they had access to greater biomass. It just seems that they did not have enough time.
- If the biomass did not come from the outside (no sabotage), what else was kept on Delta? Another species in stasis? Animals?
- Even if 2401PT was corrupted somehow by the Flood, or went slightly rampant and opened pandora's box, where did the biomass come from?
The opening entry to the Beastarium is a warning stating that no one should reanimate the entities contained within the beastarium using the index. (or something to that effect). Each halo ring has it's own index (and library). Perhaps the Gravemind had essentially taken over control of the Ring, and was therefore able to produce it's own biomass through reanimating things found coded in the library, using the index?
While I beleive this is possible, and would explain the gravemind's size by the time H2 rolled around, there's no real evidence of this. Of course, I can't help but wonder how the gravemind got a prophet stuck in him.. where did HE come from, unless being "recovered" from the index includes being given memories, etc, from the original entity that was recorded. Or was he just the prophet that got infected earlier in the game?
Or perhaps this was from an earlier covenant invasion on the ring that we've been previously unaware of?
In any event.. the gravemind certainly had his biomass.
As far as the debate over where kappa delta, etc are different sites on the same ring, or different rings, I just want to point out that the delta site is having a problem and 2401PT is referenced as being the one in charge of it, AFTER quadrant oversite. Once it was established that the delta site was in need of repair, Quadrant Oversite was queried unsuccessfully first, and then 2401 was called in. If it was the entire ring, shouldn't it have gone straight to the ring's monitor?
Also, the Installation 05 is referenced by name in the final report to installation 00 (the ark, I beleive)... why bother with greek names if you're then going to go back to calling it Installation 05 anyways?
More tellingly... They make mention of the SIX sites being adjacent facilities to the one in question, and if you made a grid of hexagons.. and labelled one "Delta" in the middle of it, you'd have 6 adjacent hexagons. Hexagons are definately Bungie significant, but the concept that they are in a 2d grid is more important for this exercise.. In the ring, they might nestle together in this 2d grid.. and wouldn't be listed in Greek numerical order.
In a 3d grid, it'd be different, as even a basic cube has 6 adjacent sides, and if you included the corners, you'd have 14 adjacent sites. This suggests to me that if they were halo installations with a circular blast radius that overlap each other in 3 dimensions, you'd have significantly more adjacent installations, or significant gaps between them.
It might make sense to assume all of the Rings have containment sites on them, considering that's part of what we know to be their function.. if they're all essentially the same, it makes sense ot use a generic term like the greek stuff for naming them.. perhaps the overall name would be something like Installation 05: Containment site [delta].
Since the greek stuff is with the 's every time they appear, it's possible it's not a perfect translation.. that's what those brackets are for. If the sites had already been translated to the greek alphabet in another translated set of transmissions, the designations would be in order in that transmission, and "fall where they may" in THIS translation, based on whatever order the reporting system used at the time.