Yes because Sukuna was actually blitzed from up close. Sukuna saw the purple the whole time, he was surprised by the output and we see him have time to raise his hands similar to when he blocked Red from Gojo. Yes, because Sukuna was using DA offensively to bypass infinity, not defensively to tank attacks. I don't understand what the correlation there is,
If being surprised by red didn't allow him to use DA in time then it's the same for purple, Sukuna wasn't able to read Gojo's output until the last moment, he tried to defend with reinforced hands not with DA and that's what he literally stated in the previous chapter.
And no there's no thing such as using DA offensively or defensively, it's the same move, you just overlap yourself with a domain without a CT which directly neutralizes any CT that comes in contact with it, so if he used DA after that, he didn't use it before, which is basically what he said, he said that he used reinforced hands, meaning hands strengthened by CE.
Gege doesn't have to narratively announce mechanics before showing them an in fact does the opposite quite often
No that's not how it works, whenever he's using DA its stated or directly implied, in fact when Sukuna used DA to block red he said he can't fully defend against blue or red, he didn't even bring up purple because he never used DA against it.
But you're assuming that he used DA in both instances where he blocked purple despite not only not being stated but also contradicted with the fact that you can't use CT and DA simultaneously.
He isn't casting though. Mahoraga has been cast, so unless you think DA would despawn Mahoraga I don't see how that point is relevant to your contention. The fact that Sukuna can still have the wheel summoned while using DA would also bolster my point. Your point is only valid if Sukuna literally cannot use DA while 10S is active in any form (including the shinigami being summoned) given that is what you were using as evidence of him not using DA.
The wheel was also casted, but whenever he used DA, the DA interrupted the adaptation and the wheel turned black.
Yes if he used DA, Mahoraga will either be despawned or will turn black and stop from functioning, which is probably the later because that's what happened to the wheel.
My point is valid because the wheel stopped from working
whenever he used DA, and it turned black, however in the new chapter the wheel color never changed and got destroyed by purple.