I don't think the post wants to be scientific and stands at the beginning to be pseudo-scientific (actually, aren't all investigations based on methods like surveys or questionnaires pseudo-scientific by definition?).

On the other hand it also says: "To be fair, it’s also true that some of the developers had given that for granted (or at least that’s what they said when asked) but it can be symptom of some underlying problem."

So it's true that most of the developers asked assumed that the code was correct already but, in my experience, I've also seen in some cases (too many) that some developers believe that they are above everything and they don't worry enough about the value that the code should delivere.

I think it's the same symptom as the "throw over the wall" problem. Some developers tend not to worry about anything that is not coding.

Pseudo-scientific, since it offers no way to determine if a piece of code meets their requirements. "Readable", "Maintainable", etc., have no a priori meaning.