Not to minimize your concerns, but I am having a tough time seeing this happen on a cruise ship. For one thing, when would a toddler or young child not be attended to? The other thing, where would a perpetrator go? The ship is only so big and there are people everywhere. I would think if a child was missing a massive manhunt would commence pretty quickly. Anyone know of anything like this happening on a cruise ship? I think I would be more worried about teens and young adults making poor decisions about entering someone's cabin. But even that is pretty risky. You can't lie about who you are to get on the ship. So if someone did such an unthinkable thing, I believe it wouldn't take much to find him.
That being said, I don't see any problem with not putting names on an FE.