Gaius Julius Caesar
Black Belt
Mark V. Wiley has researched, and trained in a number of Phillipine styles and has written a number of books on their methods and history without a relevant degree.
Don F. Draeger spent his life studying, training in, and writing about Japanese martial arts without a relevant degree and founded a field of study related to it, hoplology.
J. Lowell Lewis is a PhD (from the University of Washington) in Anthropology and Performance Studies and wrote the book 'Ring of Liberation', an antropological study of Capoeira.
Phillip Zarilli is a stage director and theater instructor that has studied and taught Kalaripayyatu extensively and wrote the book 'When The Body Becomes All Eyes', a studied of Kalaripayyatu theory and practice.
You don't need a graduate degree in MA to do the relevant work.
Because of Draeger, you actually could get a degree in Hopology from the U of Hawaii and some U in Japan for a few years.