Why do you think Leo decided to let Kevin bring Stargirl on Hot Seat?
At the time that Leo decided to let Kevin bring Stargirl on Hot Seat, her popularity was at its peak. Somewhere around Thanksgiving, the students, after laughing at her and tormenting her for weeks, suddenly embraced her. Leo was not sure what caused this change of heart. He speculated that perhaps it was because her electric enthusiasm on the cheerleading squad was so much fun, or because Dori Dilson, a quiet ninth-grader, had the courage to step up and befriend her. He wondered if it was because they, the students themselves, had changed, becoming more spontaneous and less apathetic because of Stargirl's example. Whatever the case, people liked Stargirl now. Leo, a good person at heart, had held back from letting Kevin put Stargirl on Hot Seat because he was afraid the students would use it as an opportunity to bring her down. Now that it was apparent that everyone liked her, he enthusiastically endorsed her as a candidate to be on the popular television show (Chapters 9 and 10).
Sadly, by the time Hot Seat was taped in February, a month after she had agreed to do it, Stargirl's popularity had waned. Her propensity for cheering for both sides at sports games was no longer looked upon kindly, especially since this year, Mica High had a very competitive basketball team. Students had begun to torment Stargirl again, and the Hot Seat episode was a mean-spirited disaster (Chapter 12).