Suggesting that Callum doesn’t contradict Mr. Jason’s racist teachings shows that Mrs. Paxton really doesn’t understand how dehumanizing being in school is for Callum. Few people want him here, and most people are going out of their way to make him feel unwelcome. But Mrs. Paxton then reveals her reasoning as to why Mr. Jason isn’t actually against Callum: he has nought blood. She essentially proposes that because he (presumably) loves one nought, he wants all noughts to succeed.