Tempering was something the Convocation added to Zodiark by design, as a control mechanism for stopping the uncontrollable Creation going on at the time. Whether this is true or not, I ALSO feel that the desire to sacrifice the New Life in order to restore the previous sacrifices was not Zodiark's desire, but that of the Convocation. If either or both of these things are true, then Elidibus would act no differently when freed from Tempering than he did while Tempered, since both the Tempering and the great sacrifice are things he himself wants, not things Zodiark wants.
Zodiark, as he's been presented so far, is basically just a tool. He does what his summoners ask of him, and desires nothing other than the fuel necessary to perform those tasks.
Of course, that COULD be the Big Twist - after painstakingly laying a trap for Elidibus, the Scions are able to remove him from Zodiark's control - only for nothing to change at all, as his desires remain unchanged!