Anger isn't usually an emotion that exists on its own, at least not solely; it's usually an expression of something else, at its core. Frustration or injustice are pretty common underlying causes, but so are disappointment, fear, and a variety of other emotions that can be manifested as anger or in their more direct forms.

[He offers another small shrug.]

Anger in its traditional form has its uses, but none of them apply in this situation and I'm not a huge proponent of being angry if you don't have to.