There are some assumption (or definition) problems in this article. If labor is freely mobile (as implied in this article) then there is no such thing as a "country."
Capital has always been mobile between countries for centuries; it always goes where it is treated best. Labor generally has not been very mobile. It is held in check by "citizenship".
Also, this argument goes back to the issue of deductive logic versus inductive. Many recent (inductive) studies show that increasing economic freedom results in higher GDPs per Capita. By choosing to be the most economically free country in the world, Hong Kong moved from one of the lowest GDPs per person to one of the richest ones -- exceeding the GDP per Person of the U.K.
I am a proponent of economic freedom and also believe in a "country." Therefore, assuming we still have "citizenship" (no illegal aliens) there is (or should be) no such thing as inter-country mobile labor (as described or implied in this article).
The authors are trying to make "offshoring" appear as mobile labor, when it is a one time shift of Communist countries suddenly waking up to capitalism.
The US is not the most economic free country in the world, but fortunately it's in the top 15 or so. The managed economic freedom implied by the article is a lot like forcing students to become voluntary workers: loss of freedom is always a step backwards. Keep the borders, but maximize political and economic freedom; reduce government interference; don't increase taxes on consumers by raising tariffs; encourage labor rates within the country to be flexible and movement of jobs between states to be free; maximize choice. The inductive studies have already shown the way to wealth for all citizens. A rising tide floats all boats.