KNOW YOUR LAWS:
This decision is wrong on two fronts. Firstly Nadolo does not carry the ball, so he is entitled to kick or palm or knock it back into the field of play, even if one or both of his feet lands in touch.
Secondly, as the ball does pass the invisible plane of the line, Nadolo is allowed to play the ball, even if he had both feet in touch. We saw this with Christian Wade scoring a try despite running and being in touch when he dotted a ball down.