The title implies the detail that the book fails to mention: in the end, the hijacker terrorist insane person, Tender, escapes, even though this whole novel suggested that this would be his final, celebrity worthy suicide, he being the last remaining survivor of a suicide cult. Instead, we see that in the end, although he has committed a litany of murders, he himself is scared of death. This proves that he is a murderous person, and that he uses strong emotion to bolster his attempts to get vengeance on people.
How do we know that Tender is criminally insane? Well, he tells us. When he decides to hijack a plane to kill his (real or imaginary) sister, he decides it will make him happy. He also sees a headline in the morning paper about him doing it. Later, he realizes that this was a hallucination telling him that he would become famous for this. He is motivated by popularity and fame, and hatred against life. He wants to do an outrageously evil thing and get caught for it. Hence, he admits to everything on tape, to the little black box that is specifically designed so that it survives plane crashes.
That means that he killed an officer of the law. He said that his twin brother Adam did it, but we know that if he is crazy enough to see murderous ideas arising from the headlines of the morning paper, he is also violent enough to commit murder. If he is "suicidal," then why does he escape the plane? This escapism is evidence that he doesn't mean what he says, and when he says that Adam committed the murders, what he means is that he himself commits the murders, and he doesn't believe at all in personal responsibility. But if he doesn't believe in divine judgment, why does he fear death?
