So many obnoxious things with this article. What % of people who are under 20% down payment are at 19% (likely it's negligible and most are 10%-range). Also can you just find some stats on the average mortgage rate for mortgages in the past year for those in the over- and under- 20% from a few major lenders. Regardless his whole example hinged on being 1% below 20% (which most aren't) and the bank giving you a whopping 0.45% preference (which in my experience they don't if you shop around). And in that scenario it's pretty close so anything less than 19% or a discrepancy smaller than 0.45% and things change.

And the second point about renegotiating and having preference as a high-ratio. If you were 19% at purchase, you would be over 20% at the time you renegotiate.  Unless you were well below that 19% in which case, the first example doesn't hold true.