That's his express of strong emotion, which is a very important data point for UX. Emotion trumps cool analytic fact in any day for UX. When a user is extremely annoyed, you change you UI/UX.
"Emotion trumps cool analytic fact in any day for UX."
Uh, no, it doesn't, at least not at any responsible software project I've worked on. The whole reason you run experiments, A/B testing, etc is so that this doesn't happen.
