Blocking Below the Waist

[JS63]

I have an NCAA question about this scenario. A1 positioned behind the snapper takes a direct snap and sprints to his right. He hands off to A80 who was a back positioned outside the tackle at the snap. After handing the ball off A1 continues to his right until he is well outside the tackle. A80 runs to the left and hands the ball to A81 who is sprinting to the right completing the double reverse. A1 turns around and blocks a player chasing A81 below the waist. Do you have anything? A1 was between the tackles at the snap, but can he leave the "box" and come back in and block below the waist toward the ball behind the line?