Problematic notion about Zone 5 & 6 story bits.

[Alenore]

1.) The nature of life in the universe.

For something in the world of Final Fantasy XIV to be alive, it has to have three things; a body, a mind, and a soul. This isn't an opinion; it's a scientific fact. This is why ashkin (undead) aren't alive; zombies and skeletons have bodies but no souls, while ghosts are souls with no bodies. Since Endless lack true bodies and souls, Endless are not alive. Hell, we're told as much. By the Endless.

Were Zenos, the Sahaguin that switched body, and every Ascians we defeated but not directly destroyed dead?
Were the Scions dead when their souls were ripped out of their bodies and sent to the First? They were souls without body, at that time, and had to manifest an avatar.

Are Loporrits alive? Because they don't have souls, like the good arcane entities they are classified as.
Is somebody who lost his memories and in a vegetative state alive, despite having only body and soul?

Yok Huy think people don't die because they're always remembered. Are they simply wrong? Multiple Scions think this is a great way to see death.
Even in our world, different cultures have different definition of death, and scientifically or legally speaking, is it when the heart stops beating? The brain stops showing activity?

From an in-game point of view, when do you die? When your soul is in the Aetherial sea? When it's cleansed of its memory?
Was Y'shtola dead when she was sent in the sea for so long she had to be pulled back?

2.) Emet Selch was a racist.

While you are right, that Emet Selch thought we really weren't alive, it was because he thought we were inferior. His whole talk about how we're "insects" mirrored similar views that people have used to justify genocide in real life. Since even if our souls were less dense than his, we still had souls. We were still alive based on all definitions of life, in universe.

He thought they were inferior because they had inferior souls, so I don't really understand your point (or that he's racist, when race has nothing to do with it).
He's literally a superior being to sundered people, and that's not a superlative or a "racial superiority" thing. He's a full 14/14 soul and body, while we're only a part of what Ancients used to be. He's still considering we're inferiors because our "lives" are not real because it's only a shade of what he knows life is.
Despite having memories and experiences, he's considering sundered are not alive because their "souls" don't meet his criteria for what a soul is.

You're trying to judge his conception of what is living or dead based on our own conception of death, or the Eorzean idea of what that means.
Do you think the Ancients and Eorzean had the same definition of death, and gave the same meaning to it?

3.) The Endless are essentially ghosts with questionable sentience, let alone sapience.

As mentioned above, with ashkin, the Endless are ONLY memory. No body, non soul. Basically, digital ghosts. When you shut down the terminals, you're flat out told that some will remain behind if they have "unfinished business". And while some of those that remain do seem to realize other people have disappeared, they seem unaware that the world around them has changed to a shade of grey.

Again, were the Scions dead when they had only memory and souls but no body?
Was Otis alive since he had his soul and memory?
Are the Omicrons alive since they have no body, and I'm not even sure a soul, but a robot?
Are the Ea alive despite having no body?

Is the criteria for still being alive to have at least 2 components between (body, memory, soul) ?

The Endless who remain realize everything has changed, since the guide we help in one of the aetherial current quest literally says a fountain has lost its superb, and the people he was guiding simply disappeared.

4.) Our actions are defined, in game, as a tragedy, but really the ONLY choice.

We're not doing what we're doing out of malice. We're doing what we're doing because it's the only thing we can do, in order to shave our world and other worlds, because the Endless are unsustainable. If we didn't do something, everyone in the Source would die, as a sacrifice to keep around the memory of the dead. And eventually, it would spread into other sources... And eventually, in time, still fail, since their isn't enough energy in the universe to keep the machine running indefinitely. So in time, a countless number of lives will be lost and everything still ends the same.

I've never said we were doing anything out of malice.
Actually, neither did Emet Selch when he wanted to rejoin everything, he felt he had a responsibility toward his people, just like Sphene had one towards her subject, and the Scions do towards the people of Etheirys and other reflections.

But we're with Scions who saw a recreation of life in Ultima Thule, Amaurot, the souls of the departed in the aetherial sea, and who all are scholars on all things aetherial.
We've been told by Cahciua "no can't do", and Sphene thinks she has only one solution.
We found a way to start restoring the First, started stabilizing the Thirteenth, created actual voidgates, solved tempering, G'raha and friends had people figure out working time travel and rift travel then created a summoning spell to summon someone across the rift. We managed to find enough energy to go to the edge of the universe (thanks, Mothercrystal!), we've witnessed the birth of a new star, and we literally know another race of digitalised beings who upload their consciousness in a shared network.

There's also an entire storage facility of free souls in Everkeep, ready to receive memories, and a bunch of puppets able to support these memories. Chances are some of these souls actually belonged to Endless, and they could restore them, Namikka for instance.
Had they considered memories to be important, they would have at least tried to find ways to safekeep them, give them a second chance. Just like they went out of their way to help residents of Ultima Thule.

But they didn't, and my whole point is it's because Scions don't see "just memories" as actually alive, and think the cycle of life and death is important. But Sphene and Alexandrian people don't think the same, and Scionsare somewhat imposing their beliefs on Alexandrian.

Edit : In fact, we're using the exact same argument as Emet Selch here. "Endless are not alive because they have no souls, and the cost to saving our world is their existence", against "Sundered people are not alive because their souls are incomplete, and they have to disappear if our civilization and star must come back from the tragedy that happened".