A question I would have liked to have asked Redding back in my FBS days, but never got around to it. "Pushing" is specifically defined as ..."blocking an opponent with open hands." (2-3-1-b) Why define it separately if it is to be lumped in with any kind of blocking? (2-3-1-a) I believe they truly mean pushing. The point being that a player can push an opponent in the back above the waist to try to move the opponent out of the way to attempt to reach a ball that is loose from a forward pass. Such blocking is not usually intended to create much 'punishment,' whereas a full-on shoulder or forearm block is more intended to drive an opponent to the ground with as much intensity as possible. And, it would be much more difficult to legitimately attempt to reach a loose ball while shoulder/forearm blocking the opponent. A bit of a loose distinction, I'll grant you. But I believe this to be the truth.
Perhaps it's more of a philosophy that's being taught?
Here's a question from a respected study group from earlier this year:
18. A 4/1 at the B-38. Team A's FG attempt comes up short. B26 catches the kick five yards deep in the end zone and begins to run. During the return, B33 blocks a Team A player in the back at the B-15. As B26 continues the return, A41
blocks a Team B player in the back at the 50 in his attempt to get to B26. B26 continues and carries the ball across Team A's goal line.
a. B 1/10 at the B-7.5, snap. B33 commits a foul for an illegal block in the back at the B-15. This foul will be enforced from the spot of the foul as it occurred behind the end of the related run.
A41 has not fouled as he is legally able to block in the back in an attempt to get to the ball carrier. The foul will be enforced half the distance and Team B will keep the ball. The clock will start on the snap following enforcement of Team B’s penalty (2-3-4, 2-25-10, 6-3-5, 8-4-2-b-2, 9-3-6, Exception 3, 10-2-2-c-1 & 2, 10-2-2-d-2).