But the "50% probability of Situation A (2% probability of FAI in 100 years) and 50% probability of Situation B (0% probability of FAI in 100 years)" is much more informative to the reader than "1% probability of FAI in 100 years." It exposes more about which parts of the estimate are pulled out of the writer's ass. If I know something the writer doesn't about any one of these component probabilities, I can update my own beliefs, or discuss the estimate, more usefully this way than if I'm just given a flat "1%."
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.