What's the point with that quite lackluster story in Endwalker?

[KageTokage]

If what the ironworks and G'raha did to make ShB possible actually destroyed that AU then I agree, it's not ok. I don't know if it did destroy that AU. G'raha and the Crystal tower are still here. By all evidence before me I can only conclude that the other AU still exists. But in the event it was destroyed, then yeah, bad.

One of the Tales from the Shadows sidestories confirms that the Exarch's timeline was indeed split off into its own reality...though I don't even want to think about the deeper specifics of how it exists despite the fact the causal loop would've broken by our death.