The article says that, but it can’t be the normal meaning of thaw. Thermodynamically, onbiously the innermost portion of the volume is going to warm last. But in terms of the frog’s system restart order, that order makes sense.
This frog is alive. It could detect that long-term thaw is imminent (say from sensors on its skin) and start some processes that produce heat around its heart.
FTA: In spring, the wood frog thaws from the inside outward. First the heart starts beating. Then the brain activates. Finally, the legs move.