Typically, at least two days pass between the someone's terminal cardiac arrest and the time they reach glass transition temperature, during much of this time their brain has no significant oxygen and glucose supply (ischemia). Human nervous tissue is typically unrecoverably damaged after about one hour of ischemia.

You say that as if those two durations are comparable. But what matters for the purpose of ischemia isn't the total duration of cooling, but rather the time-integral of the temperature-dependent rate of chemical reactions. And most of the contribution to that integral comes from the first ~10℃ of cooling, not the part anywhere near glass transition.