At least he didn't hang it on that super cute wall hanger above the table
I think having the visual of a coat hook should definitely help him. I, myself wouldn't hang a coat on the doorknob in someone elses house either, especially if there are other coats on it. I would probably ask where you'd want it though and definitely wouldn't use the table.
Pretty sure coats aren't allowed to be stored on top of/touching each other here.