Why did the dark-skin man act that way, try to take ALec's life jacket, and jump into a full lifeboat?

The boat was sinking and the dark-skinned man didn't have a life jacket. He was terrified, so he tried to take Alec's. The man tried to jump into the lifeboat out of fear, but the boat lurched, and he fell into the water. The dark-skinned man drowned.