Why is Malcolm's mother fired from her job in the book, X: A Novel?

Malcolm's mother, an activist for African American rights, raises her children to be educated and empowered. Malcolm recalls her teaching him about black historical figures like Queen Nzingah and Frederick Douglass, as she stated, "There's so much beauty and strength in our history" (23). Louise is later fired from her job because her employer suddenly realizes she is black. For Malcolm, this revelation is a betrayal... it seems hypocritical to him that she would preach about having pride in her race, while simultaneously pretending to be white.