If you guys talking about why his plan was backfired not because he dont know about restoration dungeon system, but he taking too much time to lay the trap.
24 hours ago before he making trap for Cyclops, he know that dungeon/wal restoration system will triggered but he dont know that anything it moved from original position will back into their own place again
Also, he did not calculate the time he took for catching predator fishes and building the trap he designed for Cyclops itself was about almost 24 hours to make it thus he barely have enough time to lure Cyclops to his trap and killed it before reset timer triggered.
Moreover, his trap are too complex to build, he actually can make simpler trap by making same hole he made, but instead of pouring water and fishes on there, make stone spears/spikes on bottom of pit to crippple Cyclops and put that gigantic rocks directly above its head as soon as it fell, so Cyclops dont have enough strength to block the gigantic rock or even destroying it completely.