Towing ignorance

Driving South on the M6 today I noticed a newish swift caravan which was about to lose its main large sky light, after trying to get him to pull over for a while with warning lights and hand signals he did eventually stop. The guy driving looked at me as though I was scraped off the bottom of a shoe, when I told him what the problem was his response was really surprising, "I'll stop at the next services and close it" I explained that it was wide open & about to come off, but still he refused to do anything about it. After witnessing a fatal accident on the M42 last year due to items coming off a roof rack, I can only say that this idiot had no thoughts for his caravan nor for the safety of others. When I got home and told my wife & Son about it they came up with another option which I had not even considered, that being because he was on his own and would not close it he had probably stolen the van and did not have a key to enter the van to close it! I really hope that this was not the case because I just left him to it when I had managed to stop him, and didn't even take his registration.