> "You can't know what the impact of your action will be if it doesn't change much"

Incorrect translation. No "if" clause need apply.

> "People can't do arbitrary things"

Also incorrect. f_actual(X) is a product of both "how much people can do" and "how much you can control/persuade them." I would model each of these with their own precise terms and relate them back to f_actual(X), and we could continue like this indefinitely, but from now on I'll just give you my reply in English: Not only does The Atomic Boy Scout not prove that a random person can bring about mass destruction (collecting random radiological material and contaminating the local area is not developing a nuke, nor is it even an effective dirty bomb, because it was neither very dirty nor a bomb; the safeguards were not lack of knowledge, either), but it still remains to be demonstrated that individuals will be radicalized by AI just by virtue of the AI being, like, super-duper smart.

> "Yes, I meant all the above specifically in the context of talking to a person, so I can't change my point of view later to be about something other than the persuasive power of words".

What domain of input do you propose, then? LLMs as rational agents have no agency but for what tokens they generate. What we hook them up to, and what they could plausibly do with what we hook them up to, has been left unsaid.