In short, do it, don't give him any ammo.
I see this job as working for the benefit of the Pt, even though indirectly.
I cover all repairs for 90days. Unless there is absolute proof the dog used it as a chew toy, with the pt's blessing...
I'd do it. If you'd do it for anyone else, do it. It's easy to say that sitting over here. Yep, sure is. I have a doc that quit me except to repair stuff I fixed before. Like the one we did a full mesh add and she still broke that 9 months later...
If you didn't say in advance, with documentation, that it is such a bad way to go that you can't warranty anything. Then you are kinda stuck.