in the novel The Road by Cormac McCarthy, why does the son apologize for what he said about the dead in the road?

The closest part that I can find in my copy is just after they feed the old man. Father did not want to share the food but the boy insists. Later the boy tells his father, "I didn't say you were wrong." The dialogue is so simple and space in this novel that you really have to dig to fined shades of meaning. Thoughts and feelings are seldom explicit. That is part of why I love this book so much.

Oops, I meant "sparse" not "space".