Frost bite CAN be caused by your internal organs in your chest cavity drawing out heat from the bodies arms and legs to keep the organs from freezing.
Yes, freezing your hand individually will cause the same effect. But when your bodies temperature gets so low, it starts drawing in heat from the non essential parts of your body so the essential parts (organs) do not freeze.
Which then allows frostbite to set in and the crystals form in your skin and the tissue starts to die. You're both right.
Anyways, yea, frozen food. I wouldn't eat it even if it is precooked doesn't mean there isn't some harmful bacteria on/in it.