Citra's understanding of what Faraday is saying suggests that immortality has made living somewhat useless: there's nothing more to learn or strive for, so what's the purpose of even being alive? Citra's anger when she grasps this suggests that though she comprehends the importance of the question, even immortal humans are still naturally offended when their purpose on earth—and by extension, their very lives—are questioned. This implies that even in an immortal world, humans do still want to live. In other words, dying hasn't yet become anything other than the scary unknown that is in the reader's world.