Rather confused how this is mental gymnastics. What he stated is literally just what happened. Unless you mean to point out the flaws in his breakdown, you don't really have a leg to stand on by just calling it "mental gymnastics".
Preventing that rejoining was also crucial to allowing the critical events involving Emet-Selch and Elidibus to play out so that the causal loop could be maintained.
It's really hard not to view at minimum everything surrounding the First as orchestrated considering that she knew leaving Ardbert lingering behind as a shadow was going to be necessary for our success.
The short story about the Watcher mentions that they did know that their sacrifice for the summoning would have to be "absolute" and remove them from the cycle entirely.
It does not specify what she told them, though, only that "precious little" about the future was disclosed. Whether that includes the Sundering or not is anyone's guess, though given that we're due for another talk with the Watcher in Myths, it wouldn't surprise me if they decided to fill in some more blanks...though honestly, them knowing and being perfectly okay with it still wouldn't make me feel much better considering that they were willing to condemn Hythlodaeus and the other sacrificed to a potentially indefinite purgatory for the sake of their ideals.
In-game text, developer commentary, and peripherals cover these things. One such instance of an interaction between Venat and her followers, which is to have taken place immediately prior to the Hydaelyn summoning, has one of them talking about the next time they meet. It's made even more apparent in the JP text, wherein the conversation has even less of a "this isn't our last goodbye" tone and leans much more into "we will definitely see you again" tone based on the selected wording.
Incidentally, Zodiark at no point consumed the souls being used to summon him. In fact, one of the primal's directives was to safeguard those souls until they could be resurrected. Every soul sacrificed to Zodiark was still "alive" within the dark primal until the moment of its destruction. The Hydaelyn summoning, on the other hand, completely used the souls up. We're given to understand the limited number of sacrifices available to Venat at the time made this an inevitability - if not at the moment of summoning, then definitely when she used her newfound power to its fullest to sunder the world. All that remains within Hydaelyn by the time she tests the WoL is her own soul and enough stockpiled aether for one last confrontation at the height of her power, after which her own soul's aether is left depleted. Using up all the gas in the tank means your soul gets destroyed. You don't get an afterlife, and you don't get to reincarnate; you are unmade forever.
The fact this topic is still going is telling me Endwalker's story must have really been a let down for some people here.
EW story was a massive letdown for me and I was generally always really into the story. I even enjoyed a good portion of the ARR story and that's generally not exactly the part that gets praised. But EW was just a mess of gaping holes, contractionary statements, fillers, wasted opportunities, repeating what you just read over and over by several different NPCs within a single quest, exposition speeches and far too much friendship stuff for me while lacking character development of the increasingly annoying Scion squad.
And that is a more personal issue but I don't enjoy having a visual novel shoved down my throat when I know from other games that you can make an engaging and interesting story and have plenty of actual gameplay.
I went from happily wiki hopping and researching for hours and caring about the characters in earlier expansions to not caring about it one bit even after reading everything carefully and thoroughly two times on two different characters. I'm done with the story.
This is the Game of Thrones season 8 of FFXIV. While Endwalker is not exactly the worst story ever told (... even though the moral disconnect is certainly something else), the fact that it ruins elements of a story people thought was genuinely good is what makes it especially awful. I don't think people would have cared as much if the game didn't have something before.
In a sense, the game is suffering from Shadowbringers' success in many ways.
I've said this a few times, but I'm certain that I would have absolutely loved Venat and held her as one of my absolute top favorite characters had the framing and presentation alone been different and less dissonant. Generally, I love ruthless, ideologically-driven women, and my umbrella for nuance within is decently wide. I will marry both Athena and Fordola, and nobody will bother me about it.
EW story felt rushed. Like they wanted to do two expansions worth and someone told them you have to do it all in one so just cut out a bunch of stuff to make it all fit. It would have made sense if they were trying to make 7.0 a new starting point for new players but that is not the case.
Even so that wouldnt justify the story lacking. The problem is EW is trying to connect so many plotlines and finish unfinished storylines all at once and it does that horribly.