A plaintiff’s lawyer would reply that improvements in workplace safety occur much more quickly from civil litigation than from criminal convictions.
Hundreds of years of laws have yet to prevent sex offenders from committing crimes. But million-dollar lawsuits quickly incentivize organizations, public and private, to police their own ranks and exclude sex offenders.
The burden of proof in a criminal conviction is high. In the case of a sex crime aboard ship, the employer sees itself as only tangentially involved in a criminal case, because in a criminal case the accused sex offender is on trial, not the employer.
In a civil case the accused sex offender is actually not the focus. They usually have shallow pockets, and it is difficult to wring money from them because of the financial effect on the offender’s dependents. So the lawyer focuses on the employer, where the money is. The employer knows this and sets up policies and procedures against possible sex crimes in order to protect itself as well as its employees
Which, a plaintiff’s lawyer would argue, is exactly how civil litigation makes the workplace safer. It forces employers to set up and monitor protective policies and procedures, something they might not do if they had not been faced with the specter of financial loss.
If the employer has set up policies and procedures to avoid the crime, and monitored them, the plaintiff’s lawyer would have an uphill battle winning a civil case (or more realistically, negotiating a big settlement). Then they might be tempted to go after the next best thing: the union, for the reasons I gave above.