I am an international student who has been accepted this cycle. It is really tough (I heard from someone that avg acceptance rate for int'ls overall is less than 1%, but not sure what the source of that number is), but there are definitely schools that will seriously consider int'ls even among state schools. Most of the top-rated private schools will look at him the same as US nationals or PRs. It took me two tries, and I have had three interviews during that time with 1 rejection (Duke), 1 wait list (UMN) and 1 acceptance (IU) post-interview. I applied to <10 schools in the first try and 15 the second time around.
My stats weren't that great as far as overall GPA goes <3.5, but BCPM was >3.7 and MCAT was >35 first time and 34 the second time, so I think that helped as far as stats go. I did have two years of military service experience in which I worked mainly on humanitarian relief efforts, and even got a recommendation from a US Army general + awards from US Dept. of the Army, so I think that probably helped as a unique experience on my resume.
Regarding the acceptance from IU, I actually lived in Indiana for a few years while my family lived there, and my dad received his Ph. D. from IU, so I think the state/school-ties helped.
UMN was fair to int'ls as well, I think. I had no state-ties there, and was invited for interview. They accept 3-5 int'ls every year.
Duke is kind of unpredictable as to who will get invited for an interview. It seems you have a lot of interviewees with "sub-par" stats, but post-interview acceptance rates are really low, so... I think Duke definitely doesn't discriminate based on visa status. I totally blew the interview (my very first interview ever and I hadn't even looked at usual questions), but even if I hadn't, I think it would have been a miracle to get accepted there.
It's tough even as a US national or PR, and maybe almost a miracle for an int'l to get accepted at a US medical school. It does happen, however, and if your friend truly has his heart set on it, then why not try?