Fast cruiser is 100% correct.
If you are going to go against the AFM then you'd better have a damn good reason.
If the approved AFM says:- "the intentional use of reverse thrust to back up the Aircraft is not permitted....." then you are a very brave Captain to attempt it nowadays especially. ( every landing can be filmed and on Facebook before you've done the parking checklist!! )
All Boeing and Airbus Jets I've flown have that statement, I haven't flown the 757.
So, is that statement in that Airlines AFM?