Basically, the problem with your second paragraph is that actions do not uniquely determine preferences.
Why is this a problem? [edit] To be clearer, I get why actions to do not uniquely determine preferences, but I don't yet get why I should care.
Sorry for the thread necromancy, but this has an easy answer: read the rest of my comment, after the part you quoted.
I have not seen any place to discuss Eliezer Yudkowsky's new paper, titled Timeless Decision Theory, so I decided to create a discussion post. (Have I missed an already existing post or discussion?)