(1st Q) Agreed, if the player was in the FOP when he attempted to catch the ball. But he was not, he was in touch. I think we would agree that a player with both feet in touch who fumbles a catch after the ball has crossed the POT and the ball goes forward (but still in touch) has not knocked-on. I am saying there is no such thing as a knock-on once the ball is in touch and the winger touching the ball has brought it into touch.
(2dQ) Not exactly. As Marauder points out in P#12, there are three Law 19 Definitions that are pertinent here:
The ball is in touch when it is not being carried by a player and it touches the touchline or anything or anyone on or beyond the touchline.
The ball is in touch if a player catches the ball and that player has a foot on the touchline or the ground beyond the touchline. If a player has one foot in the field of play and one foot in touch and holds the ball, the ball is in touch.
A player in touch may kick or knock the ball, but not hold it, provided it has not crossed the plane of the touchline. The plane of the touchline is the vertical space rising immediately above the touchline.
The third definition clearly allows for the ball being knocked back into the FOP. But the winger did not knock it back into play, he knocked-on towards his opponents goal line. The Definitions state that a player may catch, kick, or knock the ball while in touch. They do not say he can knock–on while in touch.
However, while entertaining, this part of the discussion is academic. The second definition above places the Red winger squarely in touch. The first definition above puts the ball in touch (I am assuming that the ball touching anyone in touch is the same as anyone in touch touching the ball). So, in this instance, the analysis ends with the Red winger touching the ball. No knock-on and no ball rolling into touch. Blue lineout or QTI, but no scrum.
Q.E.D. ?