We often think of complacency as a lack of any motivation, but can’t it also be seen as a kind of motivation to avoid potentially traumatic entanglements?

In a sense, this is correct, but it to us represents a kind of misnomer. The avoidance of difficulty or risk is being on one’s guard. That is an active stance to be taking even if the person is immobile entirely. Immobilization through fear is a state of active arousal, but internally and not visible externally. Complacency, on the other hand, is a non-caring about what is taking place externally or even internally. The person is simply passive and while still open to and processing sensory input, is not moved by anything to act in any way—to follow up, to become engaged, to embrace an idea or have a thought that serves as a kind of inspiration or motivation to ponder something further, or go look something up, or make a note to explore some new activity when later there is time, and so on. Complacency is a kind of cul-de-sac where one simply floats in the pond lolling in the sun and does nothing much of any consequence. So it is a state more of indifference than wanting to accomplish something, even the avoidance of a negative potential outcome.