I'll cover the key points again
1: he does not touch the ball. This is pretty much a key requirement for interfering with play
2: being in an offside position alone is not an offence. He must be in an offside position AND interfere with play, opponent or gain an advantage so unless he handles or checks a defender from his offside position, the run is of no consequence to offside. He does not interfere with Fenton because that is not the definition of interfering with an opponent. Using real world language you would probably say 'yes he does'. Using FIFA definitions, he does not.
3: When the other guy gains control of the ball, you are effectively a next phase of play so he is behind the ball and now onside
I know it's easy to go 'well that's offside because of this and...' but FIFA have narrowed the scoped right down to what specifically is offside. The decision by the AR, in my opinion, is world class and it will be used in future coaching around great decision making I am sure. I also see that there is a task force together rewriting the laws to remove anomalies and simplify the wording to understand the laws better so hopefully this law is one that gets the focus in terms of wording.