Why is Dr. Barstow biased against Meg's family in the novel, The Abduction?

Dr. Barstow is biased against the Falconers because he secretly believes, as many still do, that the family really helped terrorists despite their being cleared by the FBI. When Meg gets in trouble because other students taunt her patriotism, Dr. Barstow refuses to punish them, instead taking action only against Meg who acted out of provocation.