This is not a freak out, but instead a calculated move: “Are you in there, Kenton?”

Since his surgery, Keeton has rebuilt his sense of self around observation of human behavior, extraction of patterns into rules, and used those for his Chinese Room. Thus, “Pod Man.” This turned out to be useful in this rapidly evolving society. But Sirasti/Actual Captain need a witness, a human witness, not just a synthesist. The attack collapses Siri’s Chinese Room — the book says as much — and makes him into a Real Boy. Pain, terror, these are experiences, not translations. Like a stellar collapse of a Matryoshka Brain, the dead end black hole of self-referential, all-devouring, navel-gazing consciousness is left behind. Inefficient and alien to most other intelligences, but what is required when you want to launch a pod back to Earth, Siri inside, not Pod Man.

Once you understand who the Captain really was, well, you aren’t looking at Sirasti at all.