Thanks, I think you're right.

(For reference, I'll be defining "Newcomblike" roughly as "other agents have knowledge of your decision algorithm". You're correct that this includes problems where UDT performs poorly, and that UDT is by no means the One Final Answer. In fact, I'm not planning to discuss UDT at all in this sequence; my goal is to motivate the idea that we don't know enough about decision theory yet to be comfortable constructing a system capable of undergoing an intelligence explosion. The fact that Newcomblike problems are fairly common in the real world is one facet of that motivation.)