I would let him keep it. You would end up with an unplated uninsured vehicle, and that is a hassle to try and sell. Sounds like you are a good guy for even considering taking it back, but his mistake shouldn't become your migraine.
Hello All. Just brought home a 2022 Lariat with a 5.0, and loving it. Last truck I owned was a 1988 F150, but they are worlds apart, the current generation are really impressive. I live where it snows, and needed something when the Mustang is parked for a few months.