There were certainly ways they could have changed up that negotiation from the WN so that Procell was in control but suddenly was caught off guard, have Wright & El come in and bail him out & El gets her name, without making Procell look like he never thought about someone pointing out the oddities of his city.
Or you know, had looked like more than a 13 year old doing his first negotiation with an adult (I want to play poker with this version of Procell, jeez!).
Agreed on other comments too. What kind of argument is "you are a dungeon, a murderous collection of monsters, that is faking as a peaceful city! Now give us concessions or we'll tell!"? That's either laughably disprovable ("uhm, you are all obviously alive and unattacked... and you aren't in a tower, castle or cave. who ever heard of an open air dungeon town?") or amazingly stupid to point out ("oh you figured it out. Kill them and disappear the bodies").