Presumably, cooking/heat causes (or accelerates) some chemical reactions (like with enzymes) which turns those nutrients into something else, or the heat destro

Presumably, cooking/heat causes (or accelerates) some chemical reactions (like with enzymes) which turns those nutrients into something else, or the heat destroys the more complicated molecules, or allows the water to leech away dissolved stuff. Freezing generally means lowered rate of chemical reactions, water no longer flows, etc. So it makes logical sense that freezing keeps the nutrients intact.