Hmm. It does capture most of the essence of TDT, doesn't it?

No. Most of the interesting applications of TDT are about producing the same (or complimentary) outputs with different input. Moreover that description doesn't even imply making a correct decision on Newcomblike problems (the motivation for producing TDT in the first place). In fact, CDT augmented by the assumption that two copies of the same algorithm with the same input will always yield the same result yields CDT.

To get closer to an (oversimplified) 'essence' of TDT I'd instead suggest building from the title. CDT augmented by not caring about which point on the time dimension you are in.