My Dad was at the El Toro Marine base at the same time Oswald was. Oswald was already spouting the commie crap. I asked my Dad a WW II and Korean war vet what would happen to a marine who went around proclaiming that he was a communist. He looked absolutely shocked.
The hatred and loathing of marines to the commies was all pervasive at that time. The memory of the slaughter and torture of fellow Marines by the commies in Korea was still fresh. If Oswald was a true commie, he would have been lynched; beaten to a pulp: or harrassed out of the corps.
It is hard to believe the Corps ordered his officers to protect and leave him alone. The marines all of a sudden in Oswald's case becomes as pink as the ACLU? Not buying it.
As I recall, Oswald did have a pretty bad time of it in the Marines. All in all, he was a pathetic loser who likely seemed warped and dirty but essentially harmless to those around him — Nobody wanted to be associated with him. Not so, of course, but he had “something to prove”