Of course, the real puzzle for the audience wasn't whether or not he survived (since that's a forgone conclusion for anyone familiar with the source material), but how.
The book doesn't tell us where Cain and Seth's wives come from, but Adam and Eve are the only established source, so it's probably supposed to be a common sense conclusion.
In 3-3, he's a surprisingly accurate source of information for Phoenix, gives the more important pieces of evidence to him and stands up to Tigre without even blinking, saving Wright and Maya from a possibly gruesome conclusion.