The point is that as moral attitudes/thoughts change, societies or individuals which exist long enough will likely come to regret permanently structuring the world according to the morality of a past age. The Roman will either live to regret it, or the society that follows the Roman will come to regret it even if the Roman dies happy, or the AI is brainwashing everyone all the time to prevent moral progress. The analogy breaks down a bit with the third option since I’d guess most people today would not accept it as a success and it’s today’s(ish) morals that might get locked in, not ancient Rome’s.
The point is that as moral attitudes/thoughts change, societies or individuals which exist long enough will likely come to regret permanently structuring the world according to the morality of a past age. The Roman will either live to regret it, or the society that follows the Roman will come to regret it even if the Roman dies happy, or the AI is brainwashing everyone all the time to prevent moral progress. The analogy breaks down a bit with the third option since I’d guess most people today would not accept it as a success and it’s today’s(ish) morals that might get locked in, not ancient Rome’s.