Why David Foster Wallace called The Pale King his "memoir"

The Author's Forward to David Foster Wallace's "The Pale King" comes some 80 pages or so into the novel, so not really a forward (cute), and in many ways it is what it portends not to be. In this forward, DFW claims to be the author speaking to us, and not some character or author's creation, and he directs our attention to the publisher's disclaimer on page iv or wherever that everything in the novel is fictional and no characterizations of people living or dead, etc., or whatever the boilerplate language is - as every author (and reader) must know, these are weasel legal-speak statements and would not serve in any court of law to cover anyone's ass, but there they are in every forward - and in any case, as DFW knows, or at least he toys with the idea, there's essentially no such thing as fiction - every novel is "real" within its own terms and every novel or story, to one degree or another, draws on the "real" experiences, feelings, observations, or studies of the author - fiction is a version of reality. So in this forward DFW laughably tries to make the case that we are not reading a novel but a memoir, that DFW is telling us about real people he knew when he took a year off from school to work in an IRS regional center in Peoria. True? Who knows? - I guess somebody knows, but even if DFW did so, the novel is clearly not a memoir - but he does amusingly put in a SSI# (clearly not his, I hope) and a street address (his maybe?) - but he also claims that he's not writing some postmodern novel of Chinese boxes or infinitely receding visions in facing mirrors - but of course that is exactly what he is doing (at least in this section of this long novel): he is making us ponder what we are reading when an author addresses us in his or her own work, whether of fiction or not, about our different expectations when reading a purportedly fictional work compared with a nonfiction work, about how our perceptions shift if and when we receive conflicting information about the text we are reading - all tropes of postmodern fiction, which by claiming not to be writing he actually is (writing). This "forward" section the first to evince DFW's trademark extensive footnoting (who came first, DFW or Nicholson Baker, The Mezzanine, qv,or maybe some French writer, perhaps Perec, who DFW glancingly mentions as one of his inspirations) unfortunately in type so minute it's just about at the limits of my perception. Novel, at about page 100, still very entertaining and readable but I wonder about the coherence and the overall vision of the work - even acknowledging that this piece is posthumous and incomplete, The Pale King makes me begin to think about the difference between and the border between excellent writing and an excellent novel - the two are not the same, qv Don Dilillo's Underworld.