Harry, with all due respect, the PF told the Captain that he'd had the stick against the back stop for a while - this doesn't look like a "I wonder if I should be making inputs this large?" situation, this is a "why aren't these large inputs solving the problem?" situation from the PF's point of view.
As has been pointed out by several others on here, including myself, there are plenty of incidents where a stall was misidentified in an airliner with conventional control column with the same result. I know we would all like to think "No pilot would do that", but sometimes they do.