His anger could have been more healthily displaced, but being interrupted while you're thinking is actually the most frustrating thing ever. From my own experience the biggest problem is that sometimes when you're thinking you don't even realize it, and it's not till you're interrupted that you do. And once you're self-aware, the flow of thoughts required with the hardest kinds of thinking comes to a stop.
And if this guy is thinking about the kind of insanely hard stuff he thought about, man, I can't imagine how much that would've sucked.