9/11. The third key really. I've tried to write this succinctly and clearly twice now, and as I was procrastinating by reading another page on the web I saw an ad for some site claiming that 9/11 was not terrorists with planes, but a staged event with explosives. I admit I didn't follow the link so I don't know whether our own government is supposedly involved or some other bizarre consipiracy. I have no interest in grassy-knoll-type theories.
The thing is that when 9/11 happened everyone around us reacted as normal, civilians would - shock, horror, fear... but Kirk, isolated from the intelligence and military community of people who knew what he knew, felt what he felt, was essentially alone. For a year he had spent his days imagining just this sort of scenario. He had come up with countless plans, evaluated targets, totalled up casualties and estimated political value. He had thought like a terrorist so he could stop them. Now he had to watch it made horribly real - the nightmare he had worked so hard to avoid.
Again, I think it's vital to point out the difference between guilt and responsibility. Kirk had tried to make the warning, he had worked endless hours to stop this very thing happening. He knew he had no guilt that he had been ignored. But he retained an enormous sense of responsibility - not only for what happened, but for dealing with the new world that 9/11 ushered in.
The company he worked for did try at first to get into the Homeland Security business. They put together a proposal and asked Kirk to take a look at it. He told me later that what wasn't laughable in their pitch was illegal. They weren't terribly pleased with his assessment, and hired an outside consultant. They didn't get the contract.
When Kirk left the military he told me he felt he nothing else to prove - he had done more than enough. In his career he had helped stop a coup, saved countless lives, briefed the White House... the list goes on. Leaving when he did wasn't easy, but he could say he had made a difference. But 9/11 changed all of that. There was a great deal more to be done, things that he was uniquely suited to do. He began looking for opportunities to become meaningfully involved.