A few things jump out- this advice is not just more of the same asset 60:40 or 50:50 stock:bond asset allocation, and save 25X spending before retirement. This is a lot more demanding. He says that if you are not working, you should have 15-20 x your (expenses-(SS and pensions)) in liquid and ultra safe investments like T-bills and short term liquid notes and CDs. Now remember that these investments are designed to guard against shallow risks, which are relatively short term, but will leave one heavily exposed to deep risks which tend to be longer term, but may actually come suddenly. He more of less suggests that retired people must design to deal with shallow risks, no matter what other risks may be left unguarded.
It seems that if this book is taken to heart, and if a secure retirement is something you want, run, don't walk to get a government job if you can. Otherwise save enough for your chosen SWR, but also save another 15 -20 x(expenses not covered by COLA annuities). So non-govt workers had better have very good jobs, or no life, or both, while they try to put together this huge amount of retirement funds.