I don't think I would accuse someone of "bad husbandry" or "neglect" for using something like that as a substrate. I would recommend feeding in a separate container if they choose to do so, though.

However, there are so many other options that are worlds better choices as a substrate, it boggles my mind that anyone would choose to use aquarium rocks. I agree that within that picture itself, it looks more like a photo-set rather than an actual enclosure that animals live in regularly.

The primary purpose of substrate for snakes like ball pythons is to absorb waste. Those rocks won't absorb anything, but they would allow it to pass down below the surface the snake lives on, at least. But as stated already, keeping that clean would be a pretty big pain. Different people have different tolerances for that sort of "pain" though.

But whether you are going for something practical or something attractive...there are just so many better choices.