I recall him mentioning he's on an O-1 Visa. I assume having a published book, many other projects presented as technical publications, and lots of high profile people ready to vouch for his talent, helped overcome his lack of academic qualifications.
O-1 is a work visa, and it's temporary. If he's here to stay, then he needs a green card. O-1 in green card world is called EB-1 (National Interest) and it's a PAIN to prove. EB-2 (Advanced degree, essentially an MS) is much easier, any immigration lawyer can do it for you for a few grand and if they're quick to submit you can have your GC in 9-10 months.
