I've been thinking further on this part: "He did not have it insured yet"

Are they sure? I've dealt with lots of vehicle insurance providers, coverage, and claim issues (OMG, I've worked with/for some bozos...). Every policy included automatic coverage for a new-to-you vehicle for some provisional amount of time, allowing you time to contact them to get the coverage after purchase. Also, the driver's own insurance should have some sort of coverage for driving another person's vehicle.