This hatchling appears to be... dead?

Perhaps not. It seems to be active during the night.

Young dragons are relatively defenseless. They are born with relatively soft scales, which are shed and replaced with harder ones as the hatchling matures. Once a hatchling’s wings grow in, it typically marks the beginning of maturation. At this point they are often capable of hunting on their own and are usually left alone by their mother.

When Succo converted the egg, she was under the influence of Zephyr's control. When she allowed it to hatch,  she was under the impression it would become a female that would help Sanguinem and herself to hunt for Zephyr. When it grew to be male, Succo was so filled with fury that she demanded the Blanc and Trompo tribes freeze him, lest Kruz become yet another tyrant to cower under. As it stands, Succo was very lucky to have frozen Kruz when she did; any later, and his influence would have developed enough to control Succo and Sanguinem. With Kruz frozen at the point he is now, he is just old enough to be useful in hunting for his three elders—so long as Succo directs him with clear enough instructions, but not to try and become the Master as Gale does.

Although it is best one be cautious when Kruz is near; his powers aren't very developed, true, but it's a simple trick to make anyone's mind go a little fuzzy...