Zodiark's Codex entry what do we think about it?

[Cleretic]

So what is the end result of this supposed "angle" you keep bringing up as self-evident? If you think he's deliberately obfuscating something about Ancient society, then what is he hiding and what are his goals in doing it?

I actually wouldn't call it 'deliberate obfuscation', because that's not the main thing he does. Emet's more in the game of selective divulging of information, choosing what he reveals, how, and when to have the most dramatic and emotional effect while just... quietly dancing around the things that don't help his case.

In regards to Amaurot and the Ancients int his respect, 'what he's hiding' is, I think, actually just more of the general imperfections of Ancient society rather than any greatly damning smoking gun. When he discusses Amaurot he wants to paint them as essentially 'perfect angel' victims, both materially and morally, to really accentuate that whole 'we didn't deserve what happened to us' element. This might also be why his retelling of the events around it casually skips over everything between Zodiark's first summoning and Hydaelyn's summoning, and doesn't really bring up any dissent; he wants to ignore the parts that don't look so good for him, and also paint Hydaelyn as essentially an illegitimate rogue faction, or at least one whose reasonings don't matter enough to talk about.

One could argue he doesn't need to do that, and the facts stand on their own; an unfortunate death is always an unfortunate death, even if the victim wasn't a perfect angel. And that's not wrong; remember that the Garlemald zone in Endwalker was by and large a tragedy, and if Ul'dah exploded tomorrow, only the most heartless response would be 'good riddance to the Syndicate'. But, well, that's what Emet did, and Elpis and Pandaemonium showed it; he glossed over a lot, partially because of knowledge gaps but largely because some of those facts didn't look great for him. And from an out-of-game storytelling perspective it was probably the right move, too; we're ultimately people reading a story, and if a big-time villain is telling us about where he and all his other big-time villain friends came from, the writers have to work a little harder to make those people sympathetic and tragic than they would if, say, Y'shtola told us about her family.

All that said, I'd hardly say that I just described all of Emet. Something that really adds to his complexity is that he works so many angles over the course of Shadowbringers; it would be very possible (and perhaps not even a bad idea if you had the time) to go scene-by-scene for him and ask 'what is Emet trying to accomplish in this scene', because that actually changes constantly and yet he's never really contradictory in doing so. In some scenes he's trying to be conciliatory, sometimes he's trying to get information, or sometimes he's genuinely trying to help; in other times he's going raw scare tactics, or trying to sow doubt and distrust, or even, as Lurina said, trying to goad us into killing him.

So yeah, asking 'what's Emet's angle' actually requires very complicated answers, especially if we're talking about something that gets elaborated on across multiple scenes. Not because he's lying or hiding the truth in any of them (although he might be personally misinformed or in denial sometimes), but because he's choosing his words and what cards he reveals every single time; we need to constantly take the source of the information into account.