I'm divided on this, but since your son said he wants it "straightened out," I'd be inclined to keep it as true to his design as possible rather than anything else. It's basically his work as a child and he seems to want to keep it at some level. I'd probably rip apart and re-sew the worst of it and then finish it so he can claim to his child that it was (mostly) his childhood project. But that's me.