Not that I have any authority on this thread, but when I created the list, I was thinking about creators-- not necessarily directors-- that created a distinctive style, even if that style is not displayed in every film. Paul Greengrass, for example, in this decade created two distinctive styles-- that displayed in the Bourne series ("fast edit realistic action") and that displayed in United 93 and Bloody Sunday ("history as documentary"?). Either one would make him an auteur, but making two makes him brilliant.
The Coens are the same. At least two directing styles are recognizable, but they certainly have a visual style all their own. To borrow a phrase, it is like pornography-- hard to describe, but you know it when you see it.
Thus, GVS, although his style in some of his mainstream films is not distinctive, films like Elephant, Gerry, Paranoid Park and others are of a type, and tell a story in a unique way that is more similar to each other than to other films.
I put Charlie Kaufman on the list not because of his directing, but because all of his films have his unique touch, no matter who is directing them. I even considered putting J.K. Rowling on my list, but didn't because as distinct as she is, I don't care for her work as much as some others.
If my list were 10 and not 5, I certainly would have put Tarentino, the Coens, and Del Toro on my list. I struggled with Miyazaki, because he is my favorite auteur, and my favorite film by him was in the 00s. But he created the style outside the 00s and a lot of the distinct works of his style aren't within the timeframe. But if it were a general list (which should be created), he'd be at the top.