He advocates for a percentage of portfolio withdrawal to avoid sequence of return risk to call the drop in payouts that happen with a decline market risk instead of Sequence of returns and claims by doing this you have eliminated the sequence of return risks.
In an example in the series after the ones you posted, he showed a portfolio using a 2.5% withdrawal, because when he looked at the data a 4.5% withdrawal he was using later had a failure in year 11, would have income drop to $16,000 a year from a starting value of $25,000 with a portfolio starting with 1MM dollars!
His "solution", of having a large annual variable income swings on a 2.5% initial withdrawal rate in order to eliminate sequence of return risk to the terminal value of a all valuable portfolio is a non-starter for the vast majority of retirees.
Of course I think he also advocates a very large position (15 years) in TIPS and offsetting that with an investment portfolio that you withdraw 2.5% from so for a retirement of 40K you would need 15K per year coming off in TIPS (or 225K invested in tips) and be willing to vary income from that, with the idea being after 15 years a normal 4% withdrawal rate from the portfolio will be ok.
He seems focused with making sure there is a large estate for heirs, even tho his subtitle of his blog is retirement planning for the unwealthy. His advice is great for people concerned with leaving an estate, but for me not knowing 4 years down the road if I will be spending 31K per year or 51K per year is not a budgetable process and therefore a non-starter.