This question refers to the book To Kill a Mockingbird by Harper Lee.
In this part of the book, Tom is being questioned about his intentions with Mayella. People struggle to understand why Tom might have helped her, if he was not expecting anything from her. Tom tells the jury that he helped Mayella because he felt sorry for her.
This is a terrible feeling to have in Maycomb, and it makes the audience furious. Tom is a black man, while Mayella is a white woman. The people of Maycomb, for the most part, subscribe to the idea that white people are superior to black people. If Tom feels sorry for Mayella, this means that he feels superior, in some way, to a white person. To the people of Maycomb, this is an unforgivable display of arrogance. It is likely that they believe that, if such way of thinking became common, black people might start thinking of themselves of equal, or even superior, to white people, bringing the social order of the town into chaos.
