There also a few omissions on the list; James Brady, "Parade" magazine columnist, Pat Robertson, and Charles Whitman (Oswald is listed). I would have to classify the anti-gun Brady as an ex-marine just like Oswald. He's quite a pansy when interviewed and without pictures and proof (he served under John Chaffee in Korea), I would have a very hard time reconciling him as a marine.
BTW, the Everly Brothers only served six months active in the USMCR and were then discharged. Some kind of deal worked out with their record company and draft board so that they could avoid military service and continue recording and singing. I got that out of the liner notes on their greatest hits.
Burt Reynolds was not a marine or in any branch of the military either. He went to college on a football scholarship after high school and subsequently destroyed a knee causing him to lose the scholarship, become disqualified from military service, and turn to acting.