After going through the process of a greencard and the time it takes, i highly doubt the "shortage" has got to that point. The USCIS only has a set number of H1B visas they can give out each year and the employing company has to prove why they cant find an american to do the job. Hopefully this isn't someones misenterpretation of a foreigner already with a greencard or work visa getting a job and then someone with an axe to grind gets upset because it is seen as "taking jobs away from americans". There are plenty of american expat flying in my home country and other airlines around the world and it isn't looked at as such (of course there are some exceptions).