How is the story's theme reflected in the conversation between Hazel and George that concludes the story?

For a second, there seems to be hope when Hazel cries about her son dying. That fleeting moment disappears, and we know this because when George says "you can say that again", she repeats it, misunderstanding his statement because of her average (more like way below average) intellect.

Kurt Vonnegut's goal was not writing a story about courageous people overcoming their weaknesses and defying odds, but how society shuts down those non-conforming, defiant people.