I quite agree, I wasn’t there and neither were you of course so there may have been other factors involved. Waving by an errant driver is frowned upon as it isn’t a recognised signal and if he’s asleep or drunk, at best you’ll lose your arm anyway.
I remember VERY well on a night shift seeing hazards ahead quite some distance away. I checked my mirrors, moved over, checked my mirrors again and shhhit myself as the 3 occupants of said car all dressed in black were walking side by side towards me to the nearest ERT phone. Lucky I didn’t kill them so there is more to consider when we stop than just say you have a warning light on and are stopping. We have lots more to consider. Los things like is it a truck with a blow out and his tyre is in live lane still. We are looking behind, up ahead, across all the lanes, everywhere, in the dark trying to make the best decision, not always easy.