Thanks for your Comments. There is at least 1 more thing that is fundamentally wrong here that you didn't see (Well, you did but you didn't realize it)
To Comment on your other Comments, they are pretty good. The location is in a basement so it may have been a porcelain fixture location at one time. I never heard the 1/4" jacket rule only being for plastic boxes unless they mean that it should be longer in other boxes such as this with clamps in which case I would say that the jacket should extend 1/4" further than the clamp. Maybe someone else has a comment on this?
Can you see anything else?