Personally I'd tell him to get bent and demand all my money back *including* shipping, but I'm probably the wrong one to ask since I can't for the life of me see the attraction of a TAM. You paid, what, $370 PLUS $70 bucks shipping and the guy just tosses it loosely into a cardboard box so it seems to me he has a lot of gall to ask you to effectively pay $190 for a smashed computer that's 100% his fault.
Or, to put it another way, I'd only keep it if you're sure that the undamaged parts are collectively worth $190. Maybe they are. But I'd still be hesitant to take the deal. Someone this stupid deserves some seriously vindictive treatment.