That's why I set up the thought experiment, somewhat unnaturally, by saying: Assume that this is what everyone's secret motivation is... But I perfectly agree,

That's why I set up the thought experiment, somewhat unnaturally, by saying: Assume that this is what everyone's secret motivation is... But I perfectly agree, that the motives could be completely non-threatening. For example, if your company is all family-minded people who just want 20hr jobs so they can spend the rest with their families, then there is no real negative selection effect. But the human psyche is hard-wired to focus on threats over opportunities, and I can see how these sorts of threats weigh in heavily in managers' decision making.