Based on the voting options available I had to select #2.
If the man was a normal sized adult he would have been able to metabolize 5 drinks in four hours and not be stinking drunk. A normal 150 pound adult will metabolize one ounce of 80 proof alcohol in hour.
Five drinks may have given the young man a slight buzz but not falling down drunk. He was getting his drinks from somewhere else other than the bars or was very drunk before the five hour period that was recorded.
Perhaps some other methods can be implemented to keep people from going overboard but unless you do something intentional an adult can't "fall" overboard. The only thing that could be done to keep people from protecting them from themselves would be to enclose the outer decks in Plexiglas, chain-link or raise the railings to six feet and destroy the view and stop people, like me, from cruising. If you start implementing small measures than you will keep adding more measures until there will be no exterior spaces left on the ship for "idiots" to fall off of.
Another example of the .001% ruining it for the other 99.999%.