Tom Sawyer
Tom has hit the rivet square on the head (as always)
Its not unusual to end up having to get rid of a status message on departure and the 78 is no stranger to those, with the added bonus that a lot of BITE functions are inhibited with the refuel panel open which doesn't do much for the time pressure factor.
I can picture exactly how this was playing out because it could easily have happened to me or one of my colleagues. From the comfort of my sofa it'd be easy to say "well I would have triple checked the pin was in correctly" but when you are juggling 4/5 aircraft with varying levels of work on them and the distraction of an ever closer departure time, crew, dispatchers etc on your back then it becomes easier to see how the holes line up. (no pun intended)
I sincerely hope those involved are not castigated for this and important lessons are learned.