^ Well, to borrow an oft-used phrase ... "It's complicated."
The Caeliar's reluctance to enter the temporally unstable passages at the end of Gods of Night
was rooted in their desire to avoid causing damage to their objective timeline; they valued its preservation over their own lives.
However, the decision to sacrifice themselves was compromised by the presence of the Columbia
personnel, who would not even have been there had the Caeliar not taken them captive. From the Caeliar's perspective, deciding to sacrifice themselves to preserve the timeline was their choice to make as a society; sacrificing the humans was not
their choice to make.
In other words, the Caeliar rationalized one violation of the humans' sovereignty -- their freedom -- by telling themselves that it was necessary to protect their own seclusion, and because the humans would not be unduly harmed. But when the result of their decisions brought the possibility of death to the humans for whom they had accepted custody and responsibility, they were unable to accept that outcome.
It is, admittedly, a moral and ethical gray area. Which sins can be rationalized and which cannot? Hence ... this discussion.