Wilber is a little confused. I like much of what he teaches but some corrections on some important details have to be made for Truth's sake and for the sake of orienting an emerging integral humanity. Otherwise, allegedly insignificant errors can get magnified and carried forward as shadow into subsequent stages. OK here we go: It cannot be said that the "ultimate" is "being" in the comparative sense (as in being implying non-being either as complement (both and logic or as strict definition "either-or", no-middle-third-term-between-them logic). But understood as the one Being without any opposite, yes it can be adequately thus said. Thus, "pure being", "absolute being" and "only being" are adequate pointers and compatible with Judeo Christian negative theologies and compatible with Vedanta and other non-dual conceptual pointers to the ultimately mentally inexpressible Absolute.
Also, the once suppressed JONANG "buddhist school" recognizes that vacuity is not empty as it is (in the so called third turning of Buddhism) Tathagatagarbha (Buddha nature essence), teaching given to relieve buddhists from the wrong view and obsession of holding on to nihilistic beliefs. This is the Maha Madhyamaka (or Maha madhyamika) or Zhengtong view that is not the popular with most other politically dominant Buddhist schools and it is compatible with most of the other major spiritual non dual traditions (mystical Christianity, Vedanta, Kabbalah, Sufi). It is not exactly as the dominant Rangtong view for instance held by the Dalai Lama. In the Jonang core teachings also rests the possibility of reconciliation with some important Western, Middle Eastern and Indian thinking about the ultimate Absolute...perhaps also with the idea of “Wakan Tanka” or Great Mystery among the Sioux.
“Zhengton” means "other emptiness" and refers to "... the ultimate nature of reality is free from or empty of everything "other" than its absolute nature. In other words, a Zhentong view understands how one's own enlightened essence is empty of everything false in superficial relative reality."
http://www.jonangfoundation.org/views-practices
Also, the Pure Being doesn't need to “forget” who he it she we ( ) is in a Panentheistic sense. That relative being “forgetting” may even be as vast as the whole multi realm multiverse itself and all relative sentience holding on to some form or degree of the “primordial negation” but it doesn’t exhaust the infinite possibilities of an Absolute Eternal Being. It remains infinitely transcendental while simultaneously generative of the illusion of non-being or relative being (ex nihilo) without the need for any external substance and thus instead doing it out of His own Being. And His infinity remains absolutely free from limitations, the created, Maya, and/or the illusion of finiteness as understood in non-dual Sufism, Christianity and the mystical side of Biblical traditions. And we always remain within the All Merciful Beloved, the Source of all relative being, all possibility and whom we recognize most intimately in First Person through compassion, caring, love, life and embrace.
And that Pure Being (the only One Being- God is One) can be understood in a relative way (as in a "Sajuna Brahman” or Brahman with qualities understanding) as First Person, Second Person and Third Person, for some as Father Son Holy Spirit --- or Will, Intelligence, Love, or MUNAY (feeling in the Andes), Yachay (Knowing in the Andes) and Yankay (acting, working in the Andes). Personal will, impersonal, organizing, universal intelligence, embracing love all necessary to conceive the most perfect Being above which nothing more perfect can be conceived. Without any of those qualities the Absolute as finite mind can conceive would be incomplete. And that One Being (let’s call Him “God” to abbreviate) is Good because he it she ( ) is the Source of all being.
There are three universal expressions reflected in the four quadrants and the three Kayas; in the three main "pachas" (Hanan Pacha, Kay Pacha and Uku Pacha) in the Andes and many other ternary traditions. The actualization of the world of experience requires the reunion, meeting, encounter or confluence of the Hanan Pacha of (metaphysically prior) principles and the Uku Pacha (of ontological, future, undetermined but emerging possibilities), a meeting or encounter (TINKUY) actualized in the center of the mystery or "Chaupi" of Life (corresponding to non-dual consciousness experienced as feeling, awareness of object-knowledge and action). The Andeans didn't seem to relate too much in a explicit way to the non-dual (more of an essentialist, static, Greek, Indian, Western understanding). However, they experienced life actively embedded in it, recognizing that for anything to exist it must be in a relationship with other things and particularly with its complementary opposite or pair. They also did have - to a degree - either or, modern sense "rational" Yachay forms of thinking but emphasized relationship with all things that simultaneously were subjects ( a view which I hold...not unlike Father Thomas Berry).
Generally speaking (except for the most developed wise men and women) I also understand that they were "pre modern" (as Wilber would probably generalize), in the sense that they didn't differentiate and analyze as much in a Western Aristotelian, and modern-rational sense. However, their wisdom (by living under included middle, complementarity ultimately surpassing and including either-or, excluded middle distinctions) included integral aspects and cannot be so lightheartedly dismissed as "pre modern" and thus as pre pre pre integral altogether. This also amounts to a blind Eurocentric bias and to an insufficient and too selective inclusion of previous stage discoveries. In the Subtle Realm the intelligence of rocks and the spirits inhabiting mountains exists and they do it as subjects and can be integrally verified experientially in an integral scientific manner. All else is "integral folly and fear of properly integrating and disclosing aspects of reality due to the modern fear of being called "pre modern" or superstitious (another way of falling into the pre-trans fallacy and not living up to the challenge of truly leading the way for integral cultural transformation-evolution).
If the "Source" is ever transcendental to relative existence and to our unique individual perspective then the relation between Jesus as human and Christed Consciousness/Spirit/Logos as between God and us (also as 'sons of God') is ever perfectible, even if recognizing Source as a most intimate First Person coinciding with the essence of our unique perspective.