I was at sea when we stopped allowing passengers at night on the Sea King except for operational purposes. I don't remember that there had been any particular incident that perpetuated it. It was just an evaluation of risk versus need.
There are plenty of legitimate reasons why ship's company may be on the aircraft; famil flights is one of them. But certainly there is a risk involved. It is why certain trades that may be required to be there actually get ruet (SKT can be more specific). However, it is unreasonable to believe nobody without ruet will be onboard. The aircraft is a primary means of logistic support including pax transfer.