I think the question that needs to be answered is why does the Marine with the infinity sign have HIS plot so far from the other plot that has all six members who died. This would seem to indicate that he did not die on the helicopter with the others.
I do know for a fact that servicemembers have a choice to be buried in Arlington and that the government does provide provisions for a trip home for the funeral, then internment into Arlington. If the member wants buried somewhere else that is an option. Not all 6 may be actually buried in Arlington.
Where did the Corporal die?