they could and should have gone around at any point from the "stable by 500ft" gate
- indeed, but that is FAR TOO LATE - let's not hide the fact that they should have 'gone round' far far earlier than that. To break off an approach when it just will not work, early - at say 1500' or even earlier - is so easy, no real need for TOGA/passengers pushed back in their seats (unless the crew cannot fly manually), probably no mandatory ASR - in many respects it is not even a 'go round' as such. The idea of the 500/1000' 'stable' gates is as a final check, not to leave everything until then.