Maybe I don't understand your question. You ask why he is considered a cosmetic surgeon. Where on the website does it claim that? It says his degree is in Oral and Maxillofacial Surgery. Is it the specialty that you're asking about? This guy isn't doing boob jobs, tummy tucks or botox... Some OMFS also have M.D. degrees allowing them a broader scope, but this guy obviously only has the one degree plus the masters.
Here's an overview from the AAOMS website
"After dental school, Oral and Maxillofacial Surgeons complete four or more years of hospital-based surgical residency training that includes rotations in the general surgical service working along side other physician surgeons.
At the conclusion of this demanding program, Oral and Maxillofacial Surgeons are well prepared to perform the full scope of the specialty, which encompasses the diagnosis, surgical and related management of diseases, injuries and defects of both the functional and aesthetic aspects of the oral and maxillofacial regions. This includes preventive, reconstructive or emergency care for the teeth, mouth, jaws and facial structures. "
http://www.aaoms.org/
Cosmetic dentistry, what the other posters are referring to, is completely different from OMFS. From what I've read on the specialty board on SDN, there are a couple of schools that have cosmetic programs, but it is not recognized as a specialty. OMFS is different and is recognized as a specialty.