The man was offended that his guerdon was not what he expected. Yes, he did help the police catch the criminal, but he didn't realize that the reward offer was voided to criminals who turned themselves in.
I really hate it that I got kicked out of the soiree. And here I was hoping to meet at least one nabob in the flesh. Oh well. Maybe next year I'll have BJ help me choose more appropriate attire for the occasion.