I can't shake the feeling that for this crowd (to which the authors/researchers belong), the term guest worker has sort of become a code for "those cheap Indians". I'm also guessing the authors (and most people in this crowd) have never associated with a guest worker outside of their field of work.
I don't necessarily disagree, but I don't see why that shouldn't be just as true for people on the other side of the issue. As in, "We have a shortage, let's get some cheap Indians in here."