Except that child wasn't Ardbert as they have already stated in the 5.2 patch (you know the cutscene when Elidibert showed up and our character literally says thats not the real ardbert and Urianger as well as that moole dog confirm that our soul is still as dense as it was when he merged with us at the end of 5.0 and confirmed by dog mole in 5.1 compared to the other scions soul densities) that Ardbert's soul completely merged with ours and the child was born while ardbert was still roaming the world as a spirit.
On the subject of Emet .. nah let the man sleep...