Now I'm not saying that John Tittor is actually a time traveler or even actually John Tittor, but even if he is how could you trust him. For all we know there is not an upcoming civil war. If people actually did do what he said, possibly assasinate or silence some one they might just be playing into the hands of a new and corrupt government that wants power. They could be bringing on a world war. Who knows, all I can say is no good can come from trying to change the past, anyone traveling to the past to change it is not a good person. If the human race is doomed to die off in 2040 than that is it's destiny, but I doubt that will happen for man kind has a way of preserving itself, or being preserved at least.
My final word of advice is don't anyone be guilable enough to do anything this John Tittor says, no good can come from it. He is either lying, crazy, or naiive.