I am not judging, just trying to be as honest as possible but some finishes will crack, lift and chip very easily. Depending on the model cue, especially UV finishes.
1st, you should have been warned.
2nd, He should have offered to repair it.
This happened to me before I was educated about finishes and I refinished the cue for free, I didn't like it but I stayed professional and did it, The customer was very understanding about it. Now depending on the cue which I know which ones are prone to finish lifting, I warn them to protect myself. As cue makers and repair people, we try to help and work on as many cues as possible but their is no way we can answer for what someone else has done. It has always been the philosophy of the average customer that once you work on their cue, you are responsible for what ever happens to that cue. It's not always fair. Which is why more and more cue makers don't want to work on someone elses cue.