Your misreading what I am saying.
The Scarlet Crusade members with the Fuel Tanks on their back after you completely pull all 5 groups into a corner and AoE them to death. Apparently; make an invisible barrier, or bug the instance to the point where the Zombified Corpses will literally stop a few feet/yards before where the corner and attack the air.
I'm not reporting the spot for easy charm farming. I'm reporting that there is a possible game-breaking mechanic bug involving the instance. I have literally sat within the instance through 2 hard resets, re-killed the Scarlet Crusaders within the corner, and the Zombified Corpses are STILL getting caught on an invisible barrier or wall that was some how; magically created by me AoEing a giant group of NPCs down.