It hadn't occurred to me when looking at your table, but that could make sense. So even with the adjustments for "in kind" benefits, their spending could exceed what was in your table ? Yeah, that is possible.
Probably there isn't much savings to deplete in the bottom two quintiles, but certainly above that, people may be depleting savings beyond any earnings on investments.
Then again, retirees with savings don't want to run out of money before they die or need it for a medical emergency. And they can't count on whatever figure they've estimated for inflation. So they may actually spend LESS than their investments are earning, at least during the early years, and let it build up. That is what my folks are doing, and they are 15 years into retirement. In their case, the income taxes are due whether they spend it or not.
It would be interesting to see a comparison of money income vs. actual spending by quintiles. When I have a few minutes, I'll see if I can find something. If you find something first, please post it.