The aunt's characterization contributes to the satire by highlighting her prejudice about the man. She believes certain thoughts going on her mind regarding her perception of the man's attitude and body language, but does not actually confirm if what she thinks is factual.
When she states in her mind "he was a hard, unsympathetic man", she does so by taking her thoughts for granted and not realizing that the man's frown might have been caused by a variety of events/thoughts unrelated to her decision.
