IOW, he thinks he's found a preference function that's strictly better than any other preference function, where if you want something else (you start with a different preference function) the best way to obtain that is always to modify your preference function to this one.
>Yes - this seems like a major philosophical reach
On the contrary, I see as containing a trivial contradiction or paradox.
To evaluate what function is 'strictly better' than the rest, you need to use a ground preference function that defines 'better'; therefore, your whole search process is itself biased by the comparison method you choose to use for starters.
And even if it converges, different initial functions could guide to totally different final results. That would make it hard to call any chosen function as "strictly better than any other".