.......If as mentioned above, the local ground staff left the passengers to fend for themselves, that's a further point.
If the cockpit crew were still 'legal' in terms of duty extension to operate the short sector back home, the cabin crew can't have been too far apart in interpreting their own industrial agreement and, of course, interpretation of the legal limit. If indeed they remained on the aircraft for the empty sector home, one of them will have been by company regulation nominated to remain as the cabin safety operative anyway. ( some one correct me if current BA rules and circumstances are different )
I may be not be on solid ground here, but if this event had involved a smaller and less unionised operator, and in extremis, a perfectly serviceable aircraft shot off back into the sky leaving behind an entire complement of paid-up customers, the Captain's commercial decision might well have been to leave one or more cabin crew behind in order to ensure that the stranded passenger's best interests were protected. Legal duty extension parameters apply only to on-board aircraft operation. Any further discussion would involve active negotiated industrial agreements. Again, if as implied above, the local traffic staff are franchised and not BA employees, there could therefore now be a company rep remaining present to negotiate on the passenger's behalf, and ensure that BA's Station Manager was monitoring even if was out of hours.
Of course it's always easy to comment from a distance, and there may be more factors involved that I've overlooked, but it's still what hits the press that matters a lot.
Mutterings apart, I have a lot of sympathy for cabin crew and other airline staff who inevitably are in the front line, and as a regular fare-paying long-haul passenger with a choice of operators to my particular destination, I stick firmly to BA for plenty of reasons that surpass an occasional hiccup.........