Easy moral patch: These specific goblins have all made unambiguously evil choices that warrant a good slaying. Like kicking dogs. You're not slaying goblins because they're goblins, you're slaying dog-kickers that happen to be goblins. There are plenty of goblins who do not kick dogs, but they're not a part of this fight.
This is still a political statement that dog kickers are evil. I doubt anyone would mind that, and those that do are better off leaving my table anyway.