I’m now leaning heavily toward so5 for Antinomy, likely with a sizable 6-wing. The 6-wing is also why he comes across as somewhat loyal and with a sense of morality. Here’s what I find very 5-ish about him:
1. Antinomy is highly protective of his internal thinking and decision-making process. He refuses to let anyone interfere—and that "anyone" includes Yusei, Z-one, and (since I view them as separate) probably even Bruno.
This is classic 5 behavior when they feel insecure, or uncertain about their understanding and calculations. They don't want to discuss with others because others’ emotions and opinions interfere with their thinking process. They’d rather figure it out on their own first and then just present the result to everyone else as a done deal. This explains why Antinomy kept his regained memories a secret even while acting as, and believing himself to be, a 5D's ally. By the way, this 5-style secrecy works almost seamlessly with Bruno’s 9-style "playing pretend", effortlessly driving things to the point of no return before anyone else realizes.
2. He likes to watch from behind the scenes. Let’s not forget that, while Bruno is at the front end interacting with 5ds, Antinomy is (almost) always at the back end watching. Even when he himself interacts with Yusei, he tends to adopt a "poke and retreat" attitude—it’s less about telling Yusei what to do, and more about probing Yusei for reactions, especially for those that exceed his expectations.
This neutral, holding-off stance is maintained on a larger scale: he executes his mission to fulfill his vow to Z-one, while simultaneously putting his lot on Yusei, all while hoping that Yusei’s triumph could assure Z-one and free him of the burden of saving the future. He likely anticipated all outcomes. He could genuinely say “I started the duel to show you a new power”, while having also (mentally) prepared for the possibility that Yusei might emerge victorious. (This indecisiveness, IMHO, is also the 6-wing's suspicion leaking in).
3. The so5’s "totem": Here totem refers to an abstract, sublime ideal, which often also entails some source of power. The so5s compensate for their internal sense of depletion by attaching to this sublime being, while simultaneously becoming even more acutely aware of their own inadequacy by comparison. (“I felt ashamed watching Z-one fight without losing hope even in despair.”) The totem is usually non-human, but can be projected onto people (like the aforementioned victim, who is not entirely innocent). A classic pitfall is "Loving humanity in the abstract, but struggling to love concrete individuals." Real people — including, of course, themselves — can end up being sacrificed for the sake of the sublime ideal.
The social instinct combined with a 6-wing also brings out some so6 traits, like a rigid sense of duty and loyalty to a faction. (“I am tied to Z-one and my comrades by unbreakable bonds born of despair. My vow to Z-one is my mission.”) Even when he doesn’t necessarily agree with the faction’s ideology/objective—and is really sort of off doing his own thing—he still feels this “imperative” to go down with the ship alongside old comrades.
4.The totem for Antinomy is “clear mind”, which is courage, or the overcoming of fear. Fear of the enemy’s strength, fear of failure, and for Yusei, the fear of failing others' expectations and being abandoned.
This is a very head center theme. That "overcoming fear" is the core lesson for Antinomy and Yusei basically suggests that they are both head center types. However, their interpretations differ: Yusei (sp6) sees courage as a correct life attitude to adopt, much like the other values he has integrated from those around him. On the other hand, Antinomy (so5) has an almost worshiping relationship with (emotional attachment to) synchro summon, to the point of regarding accel synchro summon as some source of truth and power (which, given their worldview, is not unfounded). This also highlights some difference between the 6’s and the 5’s, as well as the self-preservation and the social instinct’s, core psychological traits.
