It is the same question raised by the movie, Titanic. In the movie, when all the lifeboats are launched and the ship sinks, there are 1500 people in the water about to die. Yet, to do nothing is to let the people in the water freeze and drown. It's a moral question with no easy answers and it is at the heart of the book. Within a few days he meets a well-organized group who, like him, are able to see because, for various reasons they failed to watch the meteor shower.
Survival is all that counts.
The group will move to an isolated country house. One man objects violently. He wants the sighted people to help the rest of the blind population. He is so desperate in his compassion that he kidnaps as many as he can, including Bill. Once again Bill is in a quandary.