Yeah, okay, fair. Merrin is not really confused - at least not about alternate-Estha being like that, she has a number of unanswered questions about why Golarion is like that, which seem pretty hard to answer when Estha has his current set of incentives around what to tell her and -
- and also she should probably not be operating on the assumption that everything he thinks he knows about his planet is, like, true?
Merrin isn't incredibly well-versed in the common narrative tropes around villains having a Growth Arc wherein they decide to stop doing bad things, let alone the less common tropes, because she doesn't really enjoy reading the part of the story before the Protagonist Growth Arc. But she thinks that one of the standard patterns is to have a character realize they were wrong about a matter of fact, or missing a key piece of context, and updating that false belief turns out to shift a lot of their decisionprocesses such that they no longer endorse all the villainy? So there's a trope-logic argument that perhaps Estha is not an entirely trustworthy source of facts about his planet even if he's telling her the truth as he knows it – and, separately, it seems like there's probably a normal-logic argument that it SURE SOUNDS like the doomworld torture god would not be incentivized to let his employees in his doomworld country to have accurate information on his enemies.
...what are the other things that alternate-Estha could be wrong or missing key context about? "Himself" is an obvious one, but Merrin's opaque social intuition is inclined to be especially tiptoe-y around any argument that he doesn't really reflectively endorse working for Asmodeus, and she's - not actually sure? Her Estha wouldn't but they have thoroughly established that this is not her Estha, even if he...acted surprisingly not-obviously-Evil over the entire last month? Given what she knows now it does actually seem surprising! Was it all just that, an act? Did he actually spend the entire last month resentfully wishing he could torture Merrin and refraining only because it would make her suspicious and he was hoping he could instead find his stuff and transport her back to Infernal Cheliax with her still fully cooperative?
(Merrin still vaguely wishes she could swap places with her Estha from dath ilan right now and make HIM deal with it. Pragmatically, he has some conversational skills that Merrin has not invested much in and also, like, probably an advantage to figuring out what the flaming sewage is going on in his alternate-self's head. But that's not an option she can open up by whining about it loudly enough in her head, so she's going to simply not do that.)
He could be wrong about the ultimate structure of Reality and what other things it contains other than horrible doomworld timelines?
"Would it change your mind about anything if you had additional evidence that dath ilan is just as real as Cheliax, and might be possible to contact?" she says. "I would certainly feel less conflicted about working together toward contacting dath ilan's Governance, if there were a way to do that."
It seems like proooooobably not something that will end up being an option available to them within the Outer God's game, based on her starting circumstances and...vibes...but Merrin isn't sure of that! She's not sure of very many things!