The feedback rating for you OR him have absolutely no bearing on your responsibility as a seller. You either make good on it or you don't. But not based on his feedback.

I am in NO WAY insinuating you are unethical in your dealings. Just stating my opinion.

I have wondered if there are any sellers that ONLY ship if it's insured, and tell everyone else it was lost in the mail and 'you should have insured it.' OR buyers who receive an item and claim they didn't?