“Richard Milhous Nixon. Vietnam, Watergate. There’s some good stuff too.”
Of course River sticks up for Nixon, he was her first source of comfort as a child. When she regenerates as Mels and finds Amy and Rory, they provide a stable home environment for her, even as her peers. But her earliest years were spent being tortured, controlled, and isolated by the Silence and Madame
Kovarian. So anytime she was alone or frightened she’d make a phone call and Nixon would answer. He was kind to her and promised to help her. President Nixon was the equivalent of River Song’s teddy bear.