Well... since o1 (Sept 2024), most models generate a "hidden" thinking trace before the visible answer... surely you have seen this by now: "Wait, that's wrong...", "Ah, now I have the full picture...". The model prunes dead ends when it composes the final answer.
Demanding sources for this is odd. It's literally been a headline feature of every frontier model for two years.
I guess you are "technically correct" that no model can "un-emit" tokens... but I don't think that is what anyone was saying or an interesting point to make.
Edit: see also this recent post, which details another place where revisions can happen, upstream of the reasoning token emission: