How does Noah support his assertion that “At some point, you have to choose”

Noah begins his schooling at Maryvale Academy, a private Catholic school attended by children of all different races and where students mixed and mingled freely. In the sixth grade, Noah transfers to a public school where his testing performance shows he should attend gifted classes. He is astonished to find these classes almost exclusively have white students in them, and then he realizes that the black students are attending classes for less academically advanced students. Noah decides to switch into these classes, choosing to do what he feels is best for him, despite warnings from school officials, because he feels welcomed and experiences a sense of belonging with the Black students.