It's not headcanon, its literally what is shown on the screen. Red and black energy that is the visual representation of Zamasu's will. This same energy that he can shoot out of his mouth from his sky face. So personally, the fact that we see him represented as literal energy plus he's supposedly bypassing the life cycle in DB by supposedly not becoming a soul (which wasn't stated to be destroyed) and skipping straight to something far more abstract creates a conflict of logic for me.
To be honest your argument is repetitive and circular, On the other hand because you present your argument again i also will debunk your argument this time.
1. Using visual indicator and artistic choice to debunk AE is really bad argument, with this logic i can debunk all other AE character because they have visual.
2. After Zamasu death, there is a moment before the red-black thing appear on screen, that also mean Zamasu's will have been there for a while before the whole red-black thing shot up. Not only that but also you claim that re-black thing is his energy, so if it is his energy then skip to the part where Trunks, Goku and Vegeta shot their combine energy blast, it must have damage him, but no, the combine energy blast just cause something like ripple effect like water surface, clearly indicated that IZ is metaphysical which is a trait of AE being, futher support Toei Timeline state that IZ being Zamasu's will. And don't bring the whole thing: "But IZ shot energy blast" again, not thing stated AE beign can't fight and shot physical energy blast
3. About soul, while nothing stated Trunks destroy his soul, at the same time nothing stated IZ was his soul, so you can't even prove IZ is his soul. and while we know after people die their soul remain but at the same time not nothing stated Supreme Kai follow this rule of mortal. And we don't even have a feat of Supreme Kai die, Old Kai not really die, he give his life to Goku but he still have physical body, just a halo over his head to remind that he a dead person, same with North King Kai. So we don't even know after Kai body got destroy, what happen to their suppose "soul". We we can't even prove that after Kai physically die, they still have soul left or it disappear - an unknown area.
So wrap up, Nothing can prove IZ is Zamasu's soul, while Toei Timeline stated IZ is Zamasu's will, and another back-up evidence is belong to an artbook of DB Disk which in a sense is official source. So there is no reason to disregard AE Infinite Zamasu. So please if you come back to debunk AE IZ again please have a new, better argument, i'm tired of repetitive thing.
So to the next point of this topic, and to be honest, i can't even debunk the Possibly rating to have a solid/full-blown rating either as the evidence come from secondary source which is Toei Timeline and an Artbook. And while there is no anti-feat and anti-statement in Anime, there is also no statement for IZ being AE in anime which is the primary source. So as much as i love to have a full-blown AE IZ, i don't have enough things to make this happen. So Possibly AE is fine to me.