Fun fact: Sukuna never used his True Form against Gojo despite not losing the Ten Shadows in it. The narrator also said that he could've done this at any moment and held it back the entire fight.

Ignoring the whole Gojo holding back idea, but do you know how crazy you have to be to say that you know better what a fictional character is subconsciously thinking and that the author made them say things you think they wouldn't say? Is that not genuinely insane?

Hakai has been shown being deflect by characters like Frieza, which makes it fundamentally different to Sukuna's slash. It erases existence, true, but only if the target is weak enough. It's an attack that can be tanked. WCS cuts whatever resides in the space it targets, no exceptions.

“As naturally talented”.

WCS cuts existence, by Sukuna's own words. It's not an attack that can be tanked, and if hit, Goku wouldn't survive. Of course, he would never get hit by it, but that's besides the point.

If he chanted WCS instead of Fuga

He's right, there is only one Calamity Grade Sorcerer, and it's not Yuji, Gojo or Dabura.

Sukuna's plan worked out pretty well if I remember correctly.

Gojo was never holding back, Sukuna was the one holding back. Gojo, by his own words, gave it his all. Not only that, but he has no way of destroying Sukuna's domain outside of physical damage. Sukuna wins 10/10 times. Read the manga as you clearly don't know what you're talking about.

Ask a Gojo fan how he lands Unlimited Void in the first place when Sukuna isn't late in healing his CT and watch them grow silent.

Gojo has no way to land his domain and destroy Sukuna's brain. Sukuna used no shadows during their domain clashes, so this is the same thing. Except Gojo's output will eventually fall and he can't outheal the slashes.