Well, that and we have a first-person, through-the-eyes, account of Victor meeting Stone, and at no point did Victor think holy crap, that's my brother!
Also keep in mind that while some of the historical and mythological themes mentioned are certainly deliberate, that gives us no clues as to the end of the plotline. For one thing, Stone buggered off before the war started. (There is, however, a grail.)