Su Wenyue was not someone to be trifled with. Everyone was watching her reaction. If she let Mrs. Shao off the hook easily and showed signs of weakness, then wouldn't everyone feel emboldened to bully her in the future? Even if she wasn't afraid, she would be annoyed to death.
The incident with Zhou Yao was the same, flagrantly causing her trouble. If she let such matters slide and fade away, others would surely start thinking she was an easy target. Those who couldn't find any faults with Han Yu would also start targeting her.
