The idea that DO schools accept anyone that applies is a huge misconception. Sure, their average matriculate has slightly lower stats than those in MD, but as future doctors, they still need to be accessed and proven capable through achieving academic success. It is also important they have a track record of service to convey empathy and concern.
Your friends stats aren't that good, and in my experience, DO schools place a lot of weight on having unique/impacting/long-lasting extracurriculars if the applicants stats aren't stellar. Perhaps he is just not very interesting. The best thing would be to reapply DO after a year or two of meaningful work.