the article listed with the link above, that says anyone can enter w/ photo ID, is from an article that appeared just a couple months after 9/11. Much has gone on in the world since then, unfortunately, so that article may well be outdated.
Anyone w/ the same Q--I think best bet is to go to the resort with the caveat that you might be turned away if not eligible to stay there (note--eligible is not the same as staying there, it is just a series of classifications of military, retirees, dependants, DoD civilian employees, and their guests).
I recall that I could not check in by myself last time, but could when my DoD sister and BIL arrived, and that at that time I was issued an SOG guest credential of some kind and thereafter i could come and go w/o them for the length of my stay. But that was a pre 9/11 visit and pre-expansion, so I am prepared to modify my expectations to whatever I find out at check in.