I think the study is trying to link two quite unrelated aspects through a narrow lens of anonymized "international" friendship links. What constitutes international? Is any link outside of your own country considered international?
To me, this chart seems to highlight countries that have relatively open borders with its neighbors, or countries where immigrants as percentage of population is high because of economic opportunities and such. Consider Saudi Arabia or Oman, which gets a lot of immigrants from all over the Muslim world, which seems to be one of the most "international" countries. This inference seems counter to the fact that many of those countries are not as open to international businesses as say, Singapore or Hong Kong. Nor are they poor countries per se.
To me, this chart seems to highlight countries that have relatively open borders with its neighbors, or countries where immigrants as percentage of population is high because of economic opportunities and such. Consider Saudi Arabia or Oman, which gets a lot of immigrants from all over the Muslim world, which seems to be one of the most "international" countries. This inference seems counter to the fact that many of those countries are not as open to international businesses as say, Singapore or Hong Kong. Nor are they poor countries per se.