Why must the convict and Cajun man eventually part ways?

After a week of hunting and fishing with the Cajun man, the convict learns that the pair must split ways. While leaving the hut, the pair boards a steamship where the captain informs them that they will be exploding the levees soon, causing another massive flood. The convict will be taken to an old armory which has been cleaned out and turned into a refugee camp during the floods.