I don’t think backwards causation is absurd, more or less for the reasons you sketch. Another minor reason: Some philosophers like “effective strategy” accounts of causation, according to which we define causation via its usefulness for agents trying to achieve goals. On these accounts, backwards causation is pretty trivial—just suppose you live in a deterministic universe and your goal is to “make the state of the universe at the Big Bang such that I eat breakfast tomorrow.” The philosopher Gary Drescher argues something similar in Good and Real if I recall correctly.
That said, I don’t think we are really explaining or de-confusing anything if we appeal to backwards causation to understand Newcomb’s Problem or argue for a particular solution to it.
“That said, I don’t think we are really explaining or de-confusing anything if we appeal to backwards causation to understand Newcomb’s Problem or argue for a particular solution to it.”—How come?
Perhaps I was too hasty. What I had in mind was the effective strategy strategy—if you define causation by reference to what’s an effective strategy for achieving what, then that means you are assuming a certain decision theory in order to define causation. And so e.g. one-boxing will cause you to get a million if EDT is true, but not if CDT is true.
If instead you have another way to define causation, then I don’t know. But for some ways, you are just fighting the hypothetical—OK, so maybe in the original Newcomb’s Problem as stated, backwards causation saves the day and makes CDT and EDT agree on what to do. But then what about a modified version where the backwards causation is not present?