When you log into Google, you also log into Chrome. This means that you'll have a lot of exceptions for Google websites or else a "clear history" would log you out of Chrome.
Not justifying it (I don't use chrome) but that's likely what's happening here.
In the article he explains he’s not signed into Chrome nor Google during the experiment.
This is what the “Allow Chrome sign-in” setting is for and is turned off by the post author.