How can this happen on a cruise and what should we do about it?

We recently went on a cruise on the Carnival Ecstacy. We had an incident with another person on the cruise. This person was a 34 year-old man who accused a 15 year old boy at pushing his daughter in line for the slide. When the kid said no I didn't push her, he said yes you did and took a swing at him, hitting him on the side of his face. His Uncle was sitting close by and saw what happened, so he tried to push the man back. Immediately, the man started punching the Uncle in the face and head for several minutes until other people finally could to pull the man away. And the security was not even there. The Uncle suffered from severe injuries; broken teeth, bloody nose, swollen and bruised face, a bloody ear, and scratches all over. Finally when they arrived, security took them down to their office to write a statement about what happened, not even taking him to the doctor first. When asked what was going to happen to the man, the officer said they would keep an eye on his room and our room, but there was not much to do. He paid the same amount of money as we did and just as on land things like this happen. But they would report this to the Port of Galveston authority. When we got to the port, the Galveston officer said there was not much they could do because we were in International waters, and all they could do was make the guy "sweat" a little bit. And all of us were shocked! This man hit a kid and beat another passenger and nothing was done about it! Carnival promotes their ships as a fun place to take your family and make happy memories. We left the ship in disbelief! What if the kid's Uncle was not there? Are they going to let a 34 year-old man beat up a child and simply say there is nothing we can do about it and you are on your own? We were having a great time relaxing at the pool where numerous children are, and something like this happens out of the blue. How are you supposed to protect your kid's or your family? We just think that Carnival did not do enough to protect us and make us feel safe. We will never, ever, ever, ever get on a Carnival Cruise again!