Probably because I have no real attachment with the main characters if we speak of the extinction of this society I think that they could deserve it, but not because they are evil or for their twisted morality. Because the law of evolution. Squeerats have still to reach the peak of their evolution, they are growing, fast, humans instead apparently reached their limits. They are living into an unstable balance where the minimum alteration of that balance alone (w/o Yakomaru's help) could lead, if not to extinction, to suffer heavy damages. If we mixed this situation with their
we-are-like-gods mindset that, along with engineering of the queerats and who know what else, prevented them considering Yakomaru as a threat, I'm pushed to slightly side with Yakomaru.
And for that last consideration I'm blaming firstly Satoru, and secondly Saki, who first understood his true intentions and apparently for 12 years didn't share this bit of information with anyone. (Don't know if I missed something about that issue) I got a bit surprised back then that he figured it out, out of the blue, as much as I remained surprised afterward to see that apparently he/they never informed at least Tomiko-
chan of that.
More in general speaking of guilt, even if I like Tomiko-san, she is the first who has to be blamed. Giving the in-world settings I think her longevity, paradoxically, softened her perception of the danger, leading her to think that it would be acceptable to made that experiment. But if I can agree with her in that, she tried to move forward, I could less later, when Shun's tragedy happened. IIRC Shun erased his village, didn't he? So at that point she should have strongly considered to
erase the remaining test subjects. With the in-universe morals that wouldn't have to be such a big deal. I'd like to know by the way who was the profiler who decided to put Mamoru into the experiment.
The second big issue happened in killing Mamoru first and failing at it later. You first made an experiment leaving people think freely then you don't take in consideration that it wouldn't go against you trying to take that same freedom back? What I'm saying is that if you want to kill Mamoru, again, you better kill them all, but Saki eventually, who showed the most firm mind and take her under strict checking later.
On aside note I also find Saki's voice-over apparent lack of sense of guilty nor of understanding of what happened in these days sad, but coherent with the
we-are-like-gods mindset I spoke of previously. So even if I can understand her in-universe logic, that should lead to the fact that they will not change their way of life.
Back to the actual crisis, now I'm really curious to know how did Yakomaru keep in control the child fiend. How did he unleash him against humans? From what I know he should be uncontrollable. So even if I can see Yakomaru having not raised him, but kept in captivity, somehow, still I'm curious to know why he didn't attack the squeerats and why apparently he is following Yakomaru's scheme. (unless I missed some bit of infos along the road, that it's highly probable.
)
Did Yakomaru found a way to control a karmic demon humans didn't think of?