Atticus was rather expecting an oh-shit reaction. Not that he'd done this much, but instincts told him that he should get a fight. And apparently it isn't even enough to get this guy to stop with the trying to get a hold of him thing. Still, Atticus tells himself if he can get that arm the rest of the way off, this dead thing will leave him alone. He gives a mighty shake of his head and manages to tear the arm off, parka and all.

And then he twists his whole body to get out of the grip of the other arm.