This means that, until he became a citizen, he'd immigration status in the US would have been: "exceptional alien".
That's not a status i'd give up easily. :)
I was reading an article today about an Indian nanny who saved the life of a 2 year old Israeli boy during the 2008 Mumbai attacks.
Israel honored her by granting her honorary citizenship and temporary residency in Israel.
Link : http://edition.cnn.com/2010/WORLD/meast/09/14/israel.mumbai....
"National Interest Waiver - Aliens seeking a national interest waiver are requesting that the Labor Certification be waived because it is in the interest of the United States. [...] Those seeking a national interest waiver may self-petition (they do not need an employer to sponsor them)"
http://www.uscis.gov/portal/site/uscis/menuitem.eb1d4c2a3e5b...
So, it is employment based, but without any sponsorship required from a particular employer. You're self-certifying that you're really really really good at what you do, and what you can offer to the US will benefit the US as a whole.
They will, of course, want lots of evidence to support the above.
The upside to this route is that you're not tied to a particular employer.