Yes, I would make a ship with sensors or special software to warn the pilot that there is an excessive weight before taking off. It is not wise to make a law that any stowaways would be jettisoned into space, rather than come up with a way to discover them beforehand. The pilot is right when he realizes that Marylin couldn't be blamed for not knowing the law, as she was just a girl who had never left the Earth before. His decision, to respect the law, is also understandable when one must choose between saving many lives or saving one life.
