What if we don't try to repair the body, but instead reconstruct it in a simulation? Even if the person's cells have all been mangled by ice crystals, a future medical team could conceivably map their neural network and estimate the strengths of the connections between neurons, with some futuristic high resolution scanning device. Maybe it doesn't matter that a frozen person is dead for now, if we could give their mind a virtual body transplant, and rehabilitate them in an idealized virtual environment.