That is true; he cannot demonstrate any competence. But as with many conspiracy theorists, I doubt tarkus is able to see that or would agree with that characterization. Many conspiracy theorists understandably believe that the people they encounter on the Internet will most likely be layman such as himself, and that he can bluff and bluster accordingly. A few insinuate that there really is no such thing as expertise and that what little knowledge they may have is really no different than what others have.
The question regarding his training or experience in photographic interpretation is acute. It is not a diversion. Photographic analysis and interpretation is a formally defined field in which one can earn competence through training in the proven techniques and experience applying them. Simply looking at the photograph and saying what one thinks it depicts is not photographic interpretation as is defined by its practitioners. In short, one can certainly be incompetent at it. And since few if any conspiracy theorists can describe any of the elements in its formal body of knowledge, it's safe to say that one should be assumed to have only layman's knowledge until they substantiate or demonstrate differently.
Fallacious appeals to authority can occur in several flavors. There is the obvious one, where the actor in the appeal is not a legitimate authority. But also there is one in which the question is not actually a matter that requires expertise. On the one hand, an expert in photogrammetry can describe in those terms why the photographs in question are examples of natural perspective, and may go on to supply rigorous proof in the form of projective geometry equations showing quantitatively the answer. But on the other hand, the counter examples here in this thread are given solely in the form of photographic and practical demonstrations that are within the ken of any participant. While expertise helps us understand why a phenomenon occurs, a simple demonstration proves (without needing any expertise) that the phenomenon does occur.