She cites a famous sociological study of flight attendants, which found being nice all the time is an especially draining kind of work. It can cause the emotional equivalent of repetitive stress injury.
Interesting!
(I don't worry or care much about the Seattle Chill. I'm already usually slow to get to know people, especially "normal" people, and so having that habit of mind be widespread is somewhat comfortable, plus I mainly socialize in particular subcultures were the general rules are a bit different.)