I don't understand the logic jump from point 5 to point 6, or at least the probability of that jump. Why doesn't the AI decide to colonise the universe for example?

If an AI can ensure its survival with sufficient resources (for example, 'living' where humans aren't eg: the asteroid belt) then the likelihood of the 5 ➡ 6 transition seems low.

I'm not clear how you're estimating the likelihood of that transition, and what other state transitions might be available.