I think you're rather fixated on a certain conception of "rationality" which is more like Mr. Spock than like what Yudkowsky uses it to mean.
The Yudkowskyian definition of rationality is that which wins, for the relevant definition of "win".
Specifically, if there is some clever argument that makes perfect sense that tells you to destroy the world, you still shouldn't destroy the world immediately, if the world existing is something you value. It's a meta-level up: you being unable to think of a counter argument isn't proof, and the destruction of the world isn't something to gamble with.
Yes, Yudkowsky likes thought experiments dealing with the edge cases. Yes, 3^^^^^3 grains of sand is a thought experiment that produces conflicting intuitions. Yes, the edge cases need to be explored. But in a life or death situation (and the destruction of the world qualifies as this 7 billion times over), you don't make your decisions on the basis of trippy thought experiments. (Especially novel ones you've just been presented with. And ones that have been presented by an agent which has good reasons to try to trick you.)
So, no. Again, a "logical-linguistic trick" might work on Mr. Spock, but we're not talking about Mr. Spock here.
> He's evidently a very charismatic and persuasive guy
Exactly. That's the point. If even a normal charismatic and persuasive guy can convince people to let him out, superintelligent AI would have an even easier time at it.
Long story short, it dosn't matter how he did it. All that matters is that it can be done. It can be done even by a "mere" human. If he can do it, a superintelligence with all of humanity's collected knowledge of psychology and cognitive science could do it to, and likely in a fraction of the time.
