It's in the manga. If you can't see it, set aside your bias and try again. I don't know how else to help you.
Wdym when? He got brain damage. Survived cuz Gojo let him. His domain got RCTed by Gojo. Every move Sukuna tried to make was countered.
Yeah Sukuna's fear of UV lead to him getting brain damage.
Adaptation only worked cuz of Megumi's body lol.
Yes.
Wdym so what? You're out here making Sukuna the next incarnation of Aizen for using a hostage to fight lmao. This is literally a basic plan. My 5 year old nephew could come up with a plan to use a hostage against someone
Because you're uplaying it like it's some never before seen thing that makes GOATKUNA OH SO SMART!!11!! lmao.
It's as basic as it gets. And it's dependent on Gojo.