He was very lucky to get away with it on the day, it was a terrible challenge. When showed from the reverse angle, you could see he actually speeded up after the ball had gone, and smashed the forearm/elbow into the face.

Gaskell not getting injured or making a meal of it, will probably have limited the the punishment.

With his knee as Whitehead turns. Total accident, as Foster said on Twitter he is good friends with Whitehead and toured with him for international games.

It doesn't matter if they're married.

Hopefully Foster was just carrying Whitehead's bags for him?

So during regular play, not in the act of scoring, if an attempt to dislodge the ball by Kicking instead of making a tackle was used by a saints player and he didn't quite get the ball with his foot, he is allowed to knee a player in the head?

Players get all sorts of injuries from accidental collisions made in the act of tackling unless you are suggesting he would deliberately knee somebody in the head.
Why would anyone want to apply an invented rule to saints players only?