You have no obligation...but to keep the piece....making an offer, as u did...is all that is needed to move forward. Good working partners are hard to come by and sometimes you have to bend a bit to keep the energy positive. Just remind him that you are doing this out of "the relationship " and by no means are u setting any type of precedent. Post a sign that you are not responsible for any missing items. Maybe go as far as having it in writing and have all sign a release form.
Imho. A few hundred dollars is nothing in the long run. You think you are right and he thinks he is right...so meeting in the middle seems fair. It will be way cheaper this way then trying to find someone again that has good work ethics that you sync with. Have u seen the type of workers today??? Makes me glad I dont have to deal with it anymore.