I read it at work during breaks, and people kept glancing over my shoulder at the giant 200% zoom and seeing things that shocked them. I don't enjoy books with violence, and there was plenty of it here.
As I read, I kept looking for the types of refuges. The main character is very unsocial and seems to have been that way even before the plague. He had external refuges, especially his home, which he had turned into a fortress. Why did he need so much firepower if he believed he was the last man alive?
He also has his internal refuges. He clings to the memory of a woman who betrayed him. As the story unfolds, we learn that the woman had left him before the plague. Furthermore, he has a continuous dialog with himself, and through these conversations, it is revealed that he does not really believe in himself as a good or brave man.
The townspeople were a disappointment to me also, as they seem to be to the members above. When their refuge, the town itself, was violated, instead of defending themselves, they gave up all power and became, in a way, refugees. They lost the ability to decide how to live as a community.
As a story, I think it would work much better as a short story. Lose all of the boring descriptions of every tree, path, and building. It screams "FILLER." Lose the gay sexual abuse sub-plot because it doesn't add a single thing to the plot. Instead, concentrate on his isolated existence in his fortress home, finding the dead man in the river, and the action throughout the rest of the book. I think it is a good idea and would have a good chance of selling, if it were tightened up.