I am 62 and wouldn't need to drive a car to tell if it has been abused. Having the owner drive the car should be more than sufficient. My interest would be what is under the hood and under the car. It would be nice to have it on a lift, or just up on a jack to have a good look underneith. I would expect a 9300 mile car to appear like new with no signs of leaks. Having all accessories working another consideration, but wouldn't a GM warrantee be transferrable to the next owner?
Maybe, he has an insurance protection plan that can be transferred to you. I have a buddy with a 2002 C-5 on which he had bought a full coverage protection plan. The car was drag raced and eventually had a problem with the torque converter, I think. He brought it to a recognized repair shop that evaluated the entire car and found many other things that needed to be repaired under his protection plan. A GM tech had to approve the work and it amounted to over $6K in repair work. His insurance plan resulted in a big savings. The seat tracks were replaced, apparently they had a problem with them, but he claims to not have noticed.
Your concern is understandable given the investment of the car. It is reasonable the car is like new and as advertised by the owner, but doubt remains. If your other eyes don't work out let me know and I'll shoot you some pictures with my gut feeling. Good luck with your purchase!