I'm not amending, I'm clarifying. (4) doesn't have world-changing power in itself, only through the importance of FAI implied by other arguments, and that part doesn't apply to activity of most people in the world. I consider the work on AI as somewhat significant as well, although obviously less significant than work on FAI at the margain, since much more people are working on AI. The argument, as applied to their work, makes them an existential threat (moderate to high when talking about the whole profession, rather weak when talking about individual people).

As for the character of work, I believe that at the current stage, productive work on FAI is close to pure mathematics (but specifically with problem statements not given), and very much unlike most of AI or even the more rigorous kinds from machine learning (statistics).