Nick is curious. He cannot understand the difference between his father's reaction and that of the husband. But the reader can understand that Nick's when Nick's father says the woman's screams have no effect on him, he is totally ignoring the feelings of the woman's husband who loves his wife and cannot stand to hear her scream. Nick simply asks questions about sickness, childbirth and death. Then he goes outside and, showing his immaturity, "feels secure in the feeling that he will never die."
I like Ms Mc's answer. Other things to think about:
EH shows Uncle George to be a coward. Read "Three Shots" which originally was a single story with "Indian Camp". EH does not like his uncle who would not lend financial support to Dr. H.
Suicide and untimely death are two big Hem themes. When I teach EH short stories, I use Indian Camp, The Short Happy..., and Cap of the World.