...not sure what sort of "moral debt" (second bullet point) Omar had to the country - is there some reason he should have had to contribute anything to the US economy? Its not like the military where you commit to extra years of service for the financial inducements attached to further study. He's probably already contributed more than most Americans just in his research during the years of his PhD. As an American doing a PhD in the UK, I don't feel I owe a "moral debt" to contribute to the economy here when I am done.