I don't think that's it.

If my main consideration in an interaction with a stranger is to avoid its escalating to violence, I'm going to be polite, but I'm going to be a bit reserved, not enthusiastic or friendly.

In these discussions, non-Americans often describe Americans as always happy, which is another quality I'm going to tend to avoid showing in the hypothetical interaction with the stranger because if he is feeling bitter or resentful, my being happy might set him off.