The lukew eye tracking study is for forms, not dialog boxes. And not just any forms, but it looks only at forms which have a list of left-aligned items which the user is working and scanning down. As stated: "the alignment of actions with a form’s input elements provides a clear path to completion that helps people complete forms faster."

This article is about dialog boxes. They are different. Dialog boxes usually have no form input elements and usually do not have a list of items all aligned on the left like on the lukew tracking study.