JUJUTSU KAISEN - Chapter 145

okay so like, if you don’t get the ability shenanigans even now because I didn’t really before:
Suguru Geto has the ability to absorb curses.
Fushiguro Toji has the ability to kill the Star Plasma vessel that is usually bound by fate due to having escaped the grasp of cursed energy.
The death of Amanai Riko made Tengen evolve and no longer stay human. This makes him a target for Suguru Geto’s Curse Manipulation.
How Kenjaku is forcing or manipulating humans to become sorcerers Plan A is to use Mahito’s Idle Transfiguration. This is also why Junpei was able to become a sorcerer, because Mahito used his ability on him. There are two ways to use this: The first is to make them have the potential to be sorcerers, and the second is to make those who consumed cursed objects into ideal vessels, such as Itadori.
With Suguru Geto’s technique, Uzumaki, Kenjaku is able to use Idle Transfiguration.
However, it is impossible for Kenjaku to use Idle Transfiguration on the barrier made by Tengen surrounding Japan for he lacks the cursed energy.
With Tengen’s evolution, Tengen is now the world. The merging of him and humans is like the instrumentality from Neon Genesis Evangelion, the disappearance of AT fields, the barrier to the heart.
Cursed energy would spread throughout the entire world, it’s not just that the cursed energy inside would be released into the environment, no, because of the merging, all of the humans outside of Japan would gain cursed energy.
This gives all of them the potential to be sorcerers.
The culling game is a ritual in order to prepare the merging.
The culling game will not end even if Kenjaku is killed because of the binding vow that Kenjaku made which is that he is not the game master.
Essentially, this will be a massacre. During this, Kenjaku can figure out what can make a human into a sorcerer because a lot of the sorcerers will be killing humans and wreaking havoc, which might cause the “evolution” of humans that Suguru Geto and Tsukumo Yuki talked about.

just speculation though