While that could maybe work if the cult was something that only sprung up recently, they are not. They were always acting shady and dubious as we find in Gweyr quest, they always had a tendency to brainwash people into joining them and just look at what they wear. And even before that, the way they were always presented as unabashedly evil. There is just so much disconnect between what Quinn claims the cult to have been and what it actually was/is."A vile pit o scum and villainy" feels like giving them to much credit. They're sex cult, Tollus and his inner circle might be playing for world domination as they seem to be the only remotely competent ones. The rest of the cultist seem to be complete idiots. In a scenario where he has no money, no job, nothing better to do and completely unaware of the shit that went down 20 years ago, I could see Quint coming up north(as it's apparently the place for jobless, hawkless adventurers to be) stumbling upon the sex cult, realizing that they're mostly gullible morons following a dickhead spouting what he thinks is complete nonsense and joins in for the free sex and easy work. Only after that cult sacrifices a young girl to a portal and summons an actual demon and that demon starts wrecking the place and turning other people into demons does he realize that the dickhhead wasn't spouting complete nonsense and that he's made a terrible mistake by following a crowd of idiots.
So it is hard to believe that a person, especially the one that game claims to be smart and perceptive as Quinn, can not put two and two together.
