Correct. Souls are not corporeal aether. That's why I clarified that the Endless, cannot and do not run off souls. They run off life force, which is corporeal aether. From the souls entry in our codex:
People conflate and confuse what people with the regulators are doing and what's happening in Living Memory. But the people of Living Memory are not memory aether grafted onto souls as that would be ghosts and they could have just been that in the first place, be much sturdier for it and not needed any resources to maintain it. All you'd have to do is keep them from going to the aetherial sea and they would have continued on forever. Even a city of ghosts would have been a less stupid plan. But the memory aether is removed from the soul and sent to Living Memory, while the soul is packaged into a soul cell and sent to the lower levels for distribution to living citizens. So if what she needed was souls, extracting memories from them and sending them to the other place makes no sense. She's making their physical bodies out of the stuff physical bodies are made out of. If she was making them physical bodies out of souls, well souls are eternal. She could have just left them on their original souls and none of this would have been necessary.
Usually when villains attempt to make themselves immortal, the villainy comes in the method, not the desire. Are the Ea evil? They were just minding their eternal business, chilling as blobs when the depression bird hit. And my highest moral value is self-determination, so Seymour attempting to make everyone undead violates that as does "releasing" a bunch of people without their consent, as does holding them without their consent. But given you don't end up in Living Memory without wearing a regulator, I assume the vast majority of people did consent to end up there, but we conveniently only speak to the handful who didn't want to be there. And just so you know, if I had found a way to preserve them, I still would have added a self-release option so that no one was stuck in Living Memory who didn't want to be there.