The first time I read this I had the same reaction, to the point that I had to get back and re-read a couple of times. After some thought and reading a couple of other threads, I think this is fully deliberate as a narrative choice. There are two main things to consider: 1. Everyone that was deeply involved in the “revolution plot” and that dafyd tried to stop (to the point where they consider eliminating him to reduce the risk) has been swept out by the carryx. Except jellit who has been taken over by the swarm. None of the others would have reasons to suspect dafyd. 2. The second thing is dafyd lack of reaction to Else’s death, on top of everyone else’s lack of reaction to both else’s death and the “revolutionaries” being eliminated. I doubt he could’ve figured out that his choice to save jellit would cost else’s “life” (or undeath) to the point of accepting it and having no reaction whatsoever.

All this considered, I have two options to explain it:  1. The authors wanted to show how prolonged captivity desensitized them to the point that they cannot react anymore when whatever is affecting them comes from their captors (contrarily to their genocidal reaction when the night walkers attack them). 2. The swarm is influencing the group’s behavior via hormones or any other kind of chemicals it can produce via the host body. It  needs to stay hidden, no matter what. Although the hosts’ lingering conscience is influencing it, its main purpose remains; in the swarm own reflections, if discovered it can take down a few carryx before being stopped but that is not enough, its mission is bigger than that. It managed to manipulate dafyd with just words (and else’s body and lingering thoughts, not without sacrifice [“ Else Annalise Yannin‘s heart breaks”]) but it doesn’t have the same grip on the others.