That's what I suggested briefly, that Master Vile could have cared for the child thus helping him harbor all these dark thoughts of revenge. Vile wouldnt look at his daughter and son-in-laws transformation as a good thing. Nor would the child if he was raised by Vile
I thought they already had Satan appear in Zyu (ironically he was voiced by the same guy who would eventually become Zedd's VA). He was the big floating head thing that Bandora summons.
I would assume Master Vile would've been in his own domain, the Dark Dimension. I doubt the Zordon wave would have gone there. Also, Rita and Zed could have left their son in his care there when they came back in CtD. I doubt they'd want their kid involved in such a dangerous battle.