“Children’s books have always been political, of course — that’s why they are fixtures on lists of banned or censored books. … [But] if the old image of a writer for children was a wise-child genius in the mold of Maurice Sendak — one who spoke up for kids and when necessary challenged the political powers that be, but indirectly — these days, children’s authors might not only hold signs at protest marches, they may also volunteer to strategize for a State Assembly race, or even run for office.”