I've moved a lot, and sometimes I move into a ward where I don't feel like I fit in for whatever reason. Over the years, I've learned that the problem is with me, not the others. The better I get to know people--and I mean really get to know them, beyond what is obvious--the more friends I make. I have to make the effort though. Try encouraging your friend to look around for one person he doesn't know well, and make an effort to get to know that person. Find out everything he can about them, and keep a list of the good things he learns. Then learn about someone else. If nothing else, this process, which requires him to sit with someone he doesn't already know, keeps him interested and curious.
When all else fails, I remind myself that I don't go to church for the people, I go for God. He should be there simply because God told him to be there, so he can learn to honor his priesthood. And if he's single and looking....women really do notice things like that. My daughter once gave a Sacrament Meeting talk on why girls prefer boys who honor their priesthood. She mentioned that if they don't honor their commitment to their priesthood, how can she be sure they will honor their committment to her? So if he's looking for an LDS girl, he'd best show he isn't the sort who will go inactive when the going gets tough.