how does Scout intercede between Atticus and the Old Sarum Bunch?

Scout and Jem see the mob in front of Atticus. Looking for a friendly face in the group, she recognizes Mr. Cunningham, the father of Walter from her class at school. Trying to be cordial, she innocently begins to talk to Mr. Cunningham about how Walter is a good boy, and recounts how they invited him home for dinner one day, and asks Mr. Cunningham to say hello to his son for her. Then she tries to engage him on the topic of his entailment, which she heard her father mention once, but notices that everyone is staring at her. Mr. Cunningham bends down to Scout's height and says, "I'll tell him you say hey, little lady." Scout's sincerity and innocence reminded Mr. Cunningham that what he was doing was wrong. The Cunninghams have strict code of morality and Scout was able to remind him of it.