What new problem does Matassaip present to the group as a major threat?

In chapter 6, the village chief, Kimki, has been gone quite awhile. He took a canoe across the ocean to try and reach a land he had been to as a boy (probably Southern California), to get help for his tribe, which was decimated in a fight with the Aleuts, who had deceived the tribe after gaining permission to use the island while hunting seals.
Matasaip is acting chief while Kimki is gone. Supplies have begun to run low, especially fresh water. Some villagers are panicked, but Matasaip tells them, "There are other things more important to ponder." He is referring to the return of the Aleuts. The tribe knows it is too weak to fight again, so the people have made plans to flee in canoes in case the Aleut ship comes again with its tell-tale red sail.
At first, that's what appears to happen. A ship approaches the island, and Matasaip assumes it's the Aleuts. Upon closer inspection, he realizes that this ship is smaller than the Aleut ship, with a white sail instead of red. It turns out the new ship was sent by Kimki; it is full of white men to take them to the place Kimki has gone. So what appeared at first to be a major problem was instead the villagers' salvation.