Where I disagree is that there exists a base rate of anywhere like once per century for taking a 3 in a million chance of destroying the world in any scenarios where those sorts of figures don't hold. I also disagree that rational agents will confront each other with such choices anything like so often as once per century.

If you were to wind the clock back to 1940, and restart World War 2, is there less than a 10% chance of arriving in the nightmare scenario? If not, doesn't this imply the base rate is at least once per thousand years?