Thus far in the novel Noemí has used her “pretty face” as a form of power (flattery, flirtation, etc.). Florence criticizes her for that because it's unconventional. Additionally, Florence here reveals her commitment to Howard’s ideas about eugenics and determinism. She herself once thought that it was possible for her to leave High Place, but her hopes were crushed. She’s been convinced (likely by Howard) that it’s in her nature to live and die in High Place, and she extends this same doctrine to Francis.