This is a marginal case of assisting the ball carrier. Considering the BC was largely under his own power the entire time, and he also had defenders adding to his forward movement, the amount of assistance actually provided by A56 is arguable. I think the better call in this case is a no call, with a ‘talk to’ to A56 (i.e., don’t grab, lift, etc. the ball carrier and help him move forward).
The example shown on a recent CFO video is what needs a to be called. In that one, the teammate is in advance of the BC, and he turns around, grabs the BC - who is facing backward - around the chest, lifts him, and drags the BC some 3-4 yards, with the BC offering no forward movement of his own. Now, that is assisting the BC. This example…marginal. Not worth of ruling ‘foul,’ but worthy of a caution to the suspect ‘assistant.’