Not twice the payload, John, just twice the declared cargo weight. Twice the payload would definitely have seen them out water ski-ing!
As to the Pac-man thing, there's much said about glass cockpits from those who don't really have a clue. The word "Luddite" springs to mind. Flying a glass cockpit aeroplane is a very, very long way from playing computer games. Even FS2004 - Century of Flight
It wouldn't be too difficult to have an on-board weight & balance system that automatically checks for out of limit loading and provides a warning. Even prevents the engines being started, perhaps?
