I consider it farfetched to consider images resulting from a DTR process to be more stable as such.

Not only noble metals had been employed in DTR proceses as nuclei. And if, likely in the ion form. The image consisting of metallic silver, as in classic, non-DTR images.

And we do not know how those early samples had been treated.

In a receptive layer which has not been washed or where no stabilizing means have been employed there are elements that facilitate the process of the image-forming silver turning into oxide, then ion and being either bleached or sulphidized. Both leading to the image deteriarating or vanishing.