Well first of all, in my opinion Blizzard purposely made Bolvar look how he is; yes he got burnt but his appearance is too Cataclysmish. He is seen in the cinematic but the patch brings an actual in-game model. Wether we see him before or after we kill the Lich King in the raid; then that explains the purpose of the game model in the game files but if we dont where does he come in?
Just for my thoughts
Oh and another thing, isn't the Lich King immortal? lawl.