In "All the Years of Her Life" by Morley Callaghan, how does Alfred's behavior reveal that he is immature and irresponsible?

In the story, Alfred has been caught stealing by his employer. Despite his well-developed body, Alfred's behavior reveals that he's still an immature and irresponsible young man.
First, when his employer confronts him, Alfred tries to bluster his way out of admitting his guilt. However, his indignant bravado falls flat when Mr. Carr refuses to back down. In the end, Alfred has to reach into his pocket to produce the items he has stolen: a blue compact, two tubes of toothpaste, and a lipstick. To cover his tracks, Alfred lies to Mr. Carr by telling him that this is the first time he has stolen anything from the store. Of course, Mr. Carr doesn't humor Alfred; he's observed Alfred stealing from him before, and he's furious.
When Alfred's mother gets to the store, she tries to reason with Mr. Carr. Alfred is surprised that his mother is so composed and dignified in her address. In fact, her articulate words manage to convince Mr. Carr to refrain from calling the police; Mr. Carr agrees to just fire Alfred from his job at the store. On the way home, Alfred's immaturity manifests itself; because he had expected his mother to become emotional about the theft, Alfred doesn't realize the significance of his mother's calm discourse with Mr. Carr. Essentially, her respectful and rational manner to Mr. Carr had won Alfred a reprieve from a prison sentence.
However, Alfred, in all his "excitement and relief" at having received no punishment for his crime (that he can see), fails to understand the suffering his irresponsible behavior has caused his mother. It is only later, when he observes her secretly in the kitchen, that he comes to understand how much his behavior has grieved her. So, his indignant attitude when he is confronted by Mr. Carr and, later, his thoughtless disregard for his mother's suffering reveal Alfred's immature and irresponsible behavior.