Agreed about the defensive issues. As a union winger you're part of the back three and need to cover as a fullback with all the game understanding and awareness to read the match and be in the right place at the right time. This is Ashton's major weakness.
I was once given a piece of advice by a very experienced referee assessor: "If it looks right it's probably right, and if it looks wrong it's probably wrong." This looked wrong and, offside laws aside, should probably be pinged under 10.4(m).