How did Tom feel towards Mayella, and why was this considered offensive?

While Tom is on the witness stand, Mr. Gilmer questions him as to why he chose to help Mayella without receiving monetary compensation. Tom says that he volunteered to help Mayella because he felt sorry for her. Mayella had the difficult task of taking care of all her siblings and completing the household chores by herself. Mr. Gilmer is shocked at Tom's confession of sympathy for Mayella and pauses for a long time to let Tom's comment sink in. Scout mentions that "the damage was done" and Tom realizes that he made a mistake. The all white, racist jury finds Tom's feelings towards Mayella offensive because it is against the social conventions of the time for a black man to feel pity for a white person. In 1930's Alabama, black men occupied the lowest rung of society. It was unheard of and against the unwritten Southern code for a black man to pity a white individual.