In the quote, the narrator questions the reason behind having a blind person on watch, implying it might seem unnecessary. However, he explains that the blind individual has heightened other senses, making him extremely observant and aware of tiny threats, such as a cockroach approaching from a distance.
This highlights the idea that relying on different abilities can be an advantage in dangerous or unusual situations. The character's unique skill set proves valuable, emphasizing that sometimes, what seems like a weakness can become a strength in critical moments.