I don't think it was calculated at all. Clinton just can't help himself. He is a narcissist who is obsessed with himself and his image. He is totally pissed off that he can't be the "greatest ex-president ever" and have everyone kissing his ass over his Global Initiative, because we know he didn't do squat about al Qaeda when he could have and we are not going to forget it. It's the ball and chain he will carry forever. Over time, even his harshest critics will stop talking about Monica and he will live that down. But he'll never, ever, ever live down 9/11.
I guarantee you will see the same unscripted rage in the future whenever he is questioned about 9/11. He can't lie or pout his way out of it and this he simply cannot handle.
You are right on target about Clinton's anger. Been watching his antics for over 30 years and I will guarantee that this was no show that he put on.