Haki is will and Kizaru had no will whatsoever to kill Luffy. Oda didn't bother to even give him a new named move or even draw him with basic black haki, let alone CoC. That wasn't the point of the "fight".
As for Kuzan, this is clearly CoC for anyone who doesn't have an agenda:
It's no different at all from other cases like:
In fact, it's bigger.
And lots of others. Big black lightings has always been CoC after Onigashima.
The denial comes form the fact that Admirals having CoC is the last floodgate for some, no more no less. It's the same dynamic we have seen with users trying to deny Gaban CoC after the key episode: I and others said that was CoC, but the people who didn't want that started to microanalyze the scene and straight up creating the usual checklist that never existed in the first place.
As Gaban was obvious, and was revealed explicitly ad such give some time, the same is Aokiji.
Only the usual people, since they'll have a seizure if this was true, are going to delay acknowledging it until the inevitable moment, as happened with Gaban.