I really don't understand why anyone would jump from the ship - that is not a rational act. The ship is always the safest place to be. They have watertight compartments.
"the ship as the lifeboat" is the whole reason they did not evacuate Carnival Splendor. It's a tough thing to say, but if people jumped off the ship that is not Costa's fault. That is like jumping out of a plane just because it hits turbulence.
But people don't know. I guess the shock of the moment was a lot scarier than initial news reports of a bump at dinner, right?