I finished this game today.
I chose the Sacrifice option, for several reasons, here they are in order of importance.
1. The Black Guardians logic didn't convince me, so I was to become a 'god' and live on the Star City and teach people to better themselves. Ok, but my Prophet character is not a god, just a powerful person who is potentially immortal and ageless and even that is not certain. In any event the character is killable, not in any way omniscient and cant hear prayers. Even if he could be worshipped his influence is very limited compared to other deities in fantasy and from Earth history and mythos.
2. If purportedly infinite beings like those central to real world religions or mythic pantheons cant get people to overcome their nature and live without succumbing to their fears and ambitions enough to prevent the return of the High Ones, however could an immortal adventurer who has ostensibly few if any divine powers or wisdom.
3. Knowledge of how to effect a proper cleansing is more likely to happen now while large numbers of people can see the awful consequences. This is aided by Calia/Jespars testimony to foreign leaders. It is entirely likely that a subsequent beacon would be lit properly and in the right circumstances.
4. There is no reason why the Prophet should expect to die, in fact getting to the escape pods is almost as dangerous as approaching the beacon, and Calia/Jespar managed that somehow without being Fleshless. It's a case of plot fiat both ways. I think the Prophet should have a chance to smash the stones then try to escape to the pods.
5. It seemed like the cowards way out to run when millions could be saved and the Cleansing interrupted. My character was romancing Calia and it was her preferred option, despite knowing it would cause her lovers end. escaping with her would lead to an insurmountable guilt over time, and plenty of time to consider such.
6. If the escape pods allow escape, why would the Prophet assume they would still be there. It wasnt part of Tealors plan. Some of the scholars might have realised escape to the Star City would save them and taken them. The last guy on deck of a sinking ship cannot guarantee there are any lifeboats left and those were good lifeboats with room for only two. there was no preservation order against using them to our knowledg and one wouldnt have survived the actual lighting of the beason, or maybe even the battery of the gates. Archmagister Lexil is top of the list for people who would see the opportunity, and he was still alive if not mobile by the4 time the Prophet arrived back at the temple. If Calia could make the journey after teleporting back Lexil could have from the time the beacon was lit/about to be lit.
There is another factor, it is ambiguous how long each cycle lasts, do humans have to evolve again from surrounded fauna, or do the High Ones seed a population of primitive humans they themselves save to shorted the cycle. I assume the latter but some dialogue assumes the former. My character might be waiting a very long time, alone, before they can begin with work.
There are some reasons to escape though.
1. Now the knowledge of the beacon is proliferated people can build them. Like nukes there will always be someone who wants one, some madman who wants to punish the world for reasons of their own. A cleansing might be inevitable even after the banishment of the High Ones unless the knowledge is removed. However a god-Prophet can organise the building of a beacon by their faithful workers without explaining key ingredients, y sourcing black stones themselves alone and preventing contact between different stages of the assembly team perhaps over generations. Thus a beacon could be assembled without proliferation of the technology, used properly and then dismantled.
2. The Prophet can assemble a new Numinos by returning to the Sun Temple when the cleaning has burned out. The Azrealeans cannot as they lack some required skills unless the Veiled Woman creates a new prophet - the High Ones will not feel very cooperative this time.
Spending time with Calia matters too but isn't relevant on a cosmic cycle.