The problem is what he LEGALLY needs is not an extension of his B1/B2 visa so he can illegally attend classes. He needs to adjust his status to one that allows you to pursue the medical course. The problem is that I have strong suspect he didn't enter legally if he came with the intent to attend medical school. I would suggest if he can't find an immigration attorney on his own, that his school likely has an international student office that can help.
Alternatively, he can go over to the Immigration forums at immihelp.com/forums where he'll get answers without a whole lot of disinformation noise.