Let's start with, what is your building department going to do? Did he end up getting a permit? Or will there be issues down the road - unpermited work can come back and bite you when trying to sell.

The other question you have to ask yourself is, if you show him the damage and he is willing to make repairs, do you even want him to? I wouldn't want him doing any further work for me. Even if he is capable of doing quality work, there is a whole lot of other stuff going on that I wouldn't want to deal with. It sucks for you for sure, but ask yourself how do you want to pay for this - with money or aggravation ? One way or the other, it seems you'll be paying.

Thanks Dim. He did finally get the permit, and was pretty insistent I allow him to have someone he knows who does drywall work retape and skim the seams as it will cost him less. I was certainly hesitant to agree for exactly the reason you state, but finally did; I'll keep my fingers crossed!