Now that I have had time to reflect and think about this, I would have stopped and called the cops. The damage on the car could be hundreds to thousands of dollars depending on what car. A tune up(with spark plugs) for Mercedes Benz e500 is roughly 850 bucks. I can imagine what hitting a wild animal would cost for cosmetic damage.
I hope the mans car is okay or at least have proper documentation to show the courts so that he can sue the uncle for the inconvenience that animal was.