the problem is by definition of an offside rule attacker is gaining advantage by his position, which he is not in this case. How does the position of his feet matter when he actually has to go back to collect the ball.
Also this is not accurate checking how do they know when Cuads actually passed the ball, if they want to be so accurate then they have to know exact milisecond of this, calculating it according to the picture is bullshit.
I dont know how it should be done, but for me, things like this are ruining the game, just like cancelling a goal because there was a foul 1 minute before it in the build up. totalbullshit.