This would be valid criticism if BoneyM was writing a narrative quest. He does not, so sometimes plotlines and hooks fall flat due to bad rolls or the results of vote(this is not even a first time this has happened in quest, just a first time that it did not work out for us). Such is the nature of writing dice ruled quests, and no amount of good writing can change the way it is. You either have to change framework or accept that it do be like that sometimes.
The frustrating part was not the fate of Karag Dum, which is where the dice roll came in. It's perfectly reasonable that "actually they did turn to questionable magic to survive" was the answer. The frustrating part is not having any catharsis where Borek or someone from Karag Dum comes out and justifies themselves and we vote to condemn them or not judge them or plead with them to send somebody back to Karaz Ankor or something like that. Instead Borek goes, "I know this looks bad and it is," then nopes out of the Expedition and we're left with more questions than answers.
None of that was a dice roll. That was an authorial choice.