Well, in the Chrono Trigger OVA, for the night before the Millenium or whatever, all the "mystics" were summoned in from all across time. The Nu and that furry thing too, so we can assume they count as mystics too, it doesn't mean all mystics use magic. Heck, I thought that the mystics were called demons in the jap version. And Johnny was one of them at the fair.
Plus, he seems like he's a body connected to robot parts (striking consept as in Ghost in the Shell?)
EDIT:
BTW, do not forget that in the Dead Sea, nothing decays or changes. Miguel made this pretty obvious, and as do the frozen bodies of the Acacia Dragoons.
