DozyWannabe,
This seems to be an instance of overcontrolling, because the aircraft then rolls 6 degrees to the left.
...The controls over the next 15 seconds or so look very much like a case of opposite PIO in roll...
I just agree with your presumption of overcontrolling, that's normal startle affect at AP disconnection. Watch again the magenta graph after 2:10:10, the next 15 seconds. There is not a roll oscillation, equal quantity left-right. The roll attitude is always much larger on right side, therefore Bonin constantly corrected the right roll tendency. I think he was quite busy... keeping the aircraft leveled was only one of the tasks he had to do in the same time
...Bonin's completely unnecessary pitch inputs...
He trusted some instruments that look valid. He followed the FD bars.
see final report Figure 69: Evolution of FD crossbars
Why FD didn't step out, as AP disconnected, by design?