Indeed this scenario described was observed whilst 'further exploring' UPRT 'stall/upset during go-around' training. The 'quirk' or 'effect' was quite a surprise to the 3x TREs present (at least one of which had flown most 737 Variants back to the -200) in the sim on this occasion, to the extent that the scenario was flown several times to ensure what we'd witness was indeed what we'd witnessed as an effect. Later on another FSTD (same FSTD manufacture).
Interesting all same... perhaps indeed a line of code from the 737s ancestry or perhaps indeed not valid data, albeit within the flight envelope (I.E. not the wrong side of the stickshaker or with excessive bank angles etc).