Intuitively this doesn't feel like a 'fair' problem. A UDT agent would ace the TDT formulation and vice versa. Any TDT agent that found a way of distinguishing between 'themselves' and Omega's TDT agent would also ace the problem. It feels like an acausal version of something like:

"I get agents A and B to choose one or two boxes. I then determine the contents of the boxes based on my best guess of A's choice. Surprisingly, B succeeds much better than A at this."

Still an intriguing problem, though.