Ran some tests, I think it's right.
--my data here --
I entered a 75 year time frame (gets results down to about 4 runs). The graphs don't seem to be showing anything out that far, but the text makes sense.
I did 0 portfolio, 0 spend, set a no-inflation off-chart pension income of $100,000 in 2089 (so the last year of the cycle). I set portfolio to short term treasuries to limit market influences (I think you get one year of market variation, the income is at the start of the year?). It shows a portfolio of just about 1/10 of $100,000. Makes sense if you assume 3% inflation:
0.97^75 ≈ 0.10183101
When I click inflation adjust - it is around the $100,000 value - makes sense.
Whether the spreadsheet accurately reflects the output, I guess that's a question for the maintainers of the tool.