He was almost surely trying to say that we should pick immigrants for skills (he reportedly mentioned Asia as well as Norway) but typically stated his position in the crudest terms possible.
The ensuing controversy has created a cottage industry of TV and newspaper commentators declaring proudly that they came from s***hole countries, and implying that as long as we are welcoming enough people from distressed countries, our immigration policy is on track.
This discussion is largely informed by a romantic view of the experience of the early 20th century, which is, unsurprisingly, not applicable 100 years later. …
… In short, the wave of mass migration a century ago is not a warrant for a thoughtless immigration policy today. The fact is that immigrants from rich countries tend to do better here than immigrants from poor countries, and level of education is a key factor.