There might be more to this than meets the eye. He gives a clue with the 4k timing chain change he went through. What exactly required that much money? Had it dropped it's chain before? I would want to see that bill. One should almost count on having to get a good used engine as a replacement or at least be aware it might be required. I do not think the dealer is lying to him. I also suspect the valve keepers might have dropped out. If the whole valve and stem dropped in it's going to be a mess. Thinking possibly new cylinder liner, piston, and maybe head. Then there is the overstress component when it dropped to keep in mind. Plus the original problem whatever it was. By the same token it of course would be required to take the head off or at least have a borescope look before condeming the engine. Also might make the claimed total milage suspect to some extent. The first bill and this problem should not have happened at this milage normally. There are exceptions of course. Suspect this problem occured as a result of something being missed in the first fix. I could be totally wrong though.