Do you disagree with this being "The safest option"?
Presumably you are advising that, if the insured is asked, he tells the insurance company that, "The damage was there when I bought it", or "It just appeared in the night"?
The damage was caused by the door being forced open beyond its normal limit. A bit difficult to argue that "just appeared" in the night.. There are bound to be witnesses to the damage not being there when purchased and even to how it happened.
Charges of attempting to obtain pecuniary advantage by deception, perjury, etc spring to mind.. Would the neighbour (whose wall was hit) go along with the lie? Would the previous owner/seller? Would the OP want a jail term, as well as the son?
The very, very small chance of this happening has to be weighed against the trivial amount of money involved..
A different question. I'm sure that the damage could be put right by a couple of hours of expert panel-bashing work, followed by a bit of respraying. However that, if you have to pay for it, is going to cost rather more than picking up a scrapyard one.