It would be a useful way to predict it possibly, but presumably the author meant if you have support for localization, you also provide an obvious and easy means of changing the language.
More importantly, you should be using the language an existing user has already used in the past.
Edit: come to think of it, this is less a programmer problem, and more of a UX problem. Obviously as programmers we need to take UX into consideration, but in all my products I've worked on, UX is specified already by a UX designer.