He kept quiet about the missiles. He did not want anyone knowing he had discovered them.
Segregation was an useful tool in preserving the economic and social dominance of the white southerners. With segregation the African Americans were being discriminated against and kept in socially inferior position thus enabling the whites to get better paying jobs and generally better positions thus continuing the cycle of economical dominance of the white southerners.
They did this because the soil was more fertile while it got harder to farmer further West