These are different issues.

You raised the issue of survivorship bias at the country level and gave the example of a country wiped out by a major war. So I explained why, if you're adjusting the expectations of a retiree to account for what that sort of event could do to their investments, you also need to adjust the expectations of a non-retiree, who will also be hit hard by it.

Hyperinflation is indeed a good example of something that could hurt the retiree a lot worse than someone still working, but it seems to me that it depends a lot on (1) what form the retiree's savings take and (2) what causes and consequences the hyperinflation has. For instance, if investments in the stock market lose a lot of their (real) value in a hyperinflationary episode, I'd expect that to be accompanied by a lot of job losses -- so the worst case for a retiree with a lot of stock-market investments is also bad for someone still working.