How can my friend obtain a US visa after a K1 divorce when he had not yet obtained his green card?

I appreciate that your friend respected our laws by returning home when his marriage did not work out. Unfortunately, he has no means to qualify for immigration if he has no US citizen immediate relatives. Unlike Canada and Australia, the US does not even have an official list of occupations that qualify one for immigration. Rather, a prospective skilled immigrant must get a job offer first from an employer willing and able to sponsor him. Just about every other OECD country has revised its immigration laws in the last ten years while ours remain stuck in the 1960s.