It's not about Printf. It's about how these two different kind of nil values sometimes compare equal to nil, sometimes compare equal to each other, and sometimes not
Yes there is a real internal difference between the two that you can print. But that is the point the author is making.
Go had some poor design features, many of which have now been fixed, some of which can't be fixed. It's fine to warn people about those. But inventing intentionally confusing examples and then complaining about them is pretty close to strawmanning.
It's sort of a known sharp edge that people occasionally cut themselves on. No language is perfect, but when people run into them they rightfully complain about it
EVERY language has certain pitfalls like this. Back when I wrote PHP for 20+ years I had a Google doc full of every stupid PHP pitfall I came across.
And they were always almost a combination of something silly in the language, and horrible design by the developer, or trying to take a shortcut and losing the plot.
It's confusing enough that it has an FAQ entry and that people tried to get it changed for Go 2. Evidently people are running in to this. (I for sure did)