As for me: I can get annoyed by behaviour like this but I'll always remind myself I'm not a 'regular internet user'.
As for most people I know: A lot have a dutch localization for windows and a dutch localization for Firefox/Chrome/IE. Quite a few (about 30%) have an english localization for their browsers (either because they have an english localization for windows or because they like 'consistent menus across all applications'.
I do agree with the author that geolocation should not be the first choice (cookies should be) but as a second choice it's better than the 'Accept-Language' header.