I have often thought similar to Gambit. Sure, it's a computer game with its own set of laws and physics, but the narrative has to be consistent within them boundaries. It asks the question - why did Chaos not just place a big ol' lump of wall at the entrance to stop people getting in? We can't break walls down without some trigger in DM. This would give Mr Chaos all the time he needs to figure out the Zo Kath Ra spell. But asks further questions.
The manual (story) states that a botched attempt at extracting the power gem causes the universe to explode and Chaos was split off from the Grey Lord. Chaos somehow managed to take over the dungeon, and as he is, shall we say, "a bit on the evil side", twisted the Grey Lord's experiments into puzzles and traps to mock him. So this could possibly explain why the dungeon is the way it is - Chaos invited people in to torment them, giving them false hope and treasures, only to eventually torture them to death. His lust for blood and trophies was ultimately his undoing, even though he knew the Firestaff could be his fate if it was reclaimed.
Now what about Lord Librasulus and Lord Order? Are they not the same person? I believe so, as opposed to Chaos, Order and a third being left over from the Chaos/Order creation. Lord Order was the other half of the splitting, and in reality is just as evil as Chaos. In order to regain form and be able to enter the dungeon himself he needs the Firestaff. He renames himself Librasulus to hide his intent (and to explain why his appearance had changed) and instructs Theron to go and fetch it. The story hints though that he had collected his thoughts and now knew the spell - but he never gave it to Theron. We all know what happens when we bring the Firestaff to the entrance
Interestingly the first hint book states that Fuse from the Powerstaff+ is actually the fusing fluxcages together into one large cage. The second hint book scribes that fusing Chaos when surrounded by fluxcages (and/or walls and yourself) will teleport Lord Order in his true colours to the same square where they ultimately amalgamate into the Grey Lord.
Or something like that....