Tikent, think of it this way, would you want someone to tell you want pictures to have in your room? I didn't think so. As jjariz had said above, let him enjoy what he wants.
With Alzheimer's/Dementia, some people go back in time and they don't remember being married or having children.
My Dad had sundowner's, and during that time frame his mind was back in the 1940's, not in the current world.
From reading your other post, I would say hang those car pictures, and let him call the car when he needs something, and yell at the car when he does not get his way. Probably not very helpful,, but forgive me my mood tonight! Sometimes you just can not get through to them, their brain is broken and things become all about them.
With Alzheimer's/Dementia, some people go back in time and they don't remember being married or having children.
My Dad had sundowner's, and during that time frame his mind was back in the 1940's, not in the current world.