Following those steps I set both B15 and B16 to 25%, and B17 to 0%. I didn’t change anything else on the sheet. The future value of the accounts of course were different, but the retirement after-tax draw was precisely the same in both scenarios.

I don’t think you can find numbers to plug in that prove your point. The only way that the taxable account will outpace the tax-deferred account is if you withdraw at a higher marginal tax bracket, or in some scenario where your preferred rate at withdrawal is actual negative.

Alternatively, one might interpret the phrase “wipe out the savings” to mean that the savings were completely negated by the 0% preferred tax rate, but even in that case, at worst you’ve broken even. I don’t think that fits the definitions of losing the preferred tax rates or converting preferred income into ordinary income.

Overall I do agree with your main point that tax deferral is not the same as tax avoidance, and that some people overstate the benefit of the former. Just as you’ve previously posted that some people overstate the benefit of the latter when it’s done by preferring a Roth account over a deferred account.

Try setting the the marginal tax rate at both contribution and at withdrawal to the same percentage. (So the same value in cells B15 and B16.) And then leave set the preferred rate to 0% meaning the person’s income is low enough that ordinary income is sheltered by deductions and personal exemptions and qualified dividends and long-term capital gains get to “fill up” the 10% and 15% brackets.