You may want to contact the owner of the store & see what kind of insurance they have for this sort of thing. They'd have to pay a very high premium because things like this can happen.
I agree with showing the store footage to AC & let them charge him with all they can. Animal Abuse! for one. His dog should have been muzzled, he 'knew' the dogs temperament.
& you can file suit against him & he pays 'all' the Vet bills. All, not part. & he pays court costs, too.
This poor dude is really in trouble with AC & you after him.