It's different because the problems it talks about aren't determined by what decision is made in the end, but by the state of mind of the person making the decision (in a particular and perhaps quite limited way).

You could probably show that a mixed-strategy-aware problem could make the proposed theory fail in a similar way to how causal decision theory fails (i.e. is reflectively inconsistent) on Newcomb's problem. But it might be easy to extend TDT in the same way to resolve that.