It's not a matter of depth perception. It's not even a matter of depth. Rather, it's the dearth of depth. Depth refers to who is farther away from the camera. Can you tell from looking at this?
But, what exactly are we seeing here? Which one of them is "whole"?
What was the physical arrangement between those two people, as they stood in the doorway, to result in that photographic outcome? And whatever you think it was, you need to reproduce it with your own camera. When I tried it, I got what I expected.
I get it about the depth, but do you, Backes? Because the man in back is deeper, because I am in front of him, partially, I am covering up part of him, but he is not covering up any part of me. You can't say that this below is a whole person.
Here is how it looked in the Altgens photo as it was published.
So, it's the opposite of what Backes said. The problem is that he has no depth perception, that he doesn't know how to recognize depth, that he doesn't understand how depth affects the objects in a photograph.