This is already the standard they operate under in the series. To give some context, the term "Conqueror's Haki infusion" has only ever been used once in the series, as Oda typically states what an ability is only once or twice before moving on, expecting the reader to be competent enough to understand the visual indicators he provides for said ability. This is also how he has treated Advanced Armament Haki and many other Haki abilities. We almost never get direct verbal confirmation, and even databook confirmations don’t always specify whether a character is capable of using advanced variants. In some cases, like with Zoro, they don’t even include it at all.
I get that to an extent from Conq in general, Adv Conq not so much.
Their visual distinction is practically 0 outside of when two Adv Conq clash, sky split feats, or attacking without touching someone.
Just because Oda isn't always privy to direct confirmation doesn't mean we should start drawing hard lines in the sand for absolutes that conq and adv will always have.
I'm proposing BB used ACoC because we see him infuse it into his attacks in the panels, which is what ACoC is.
Just because red lightning is coming off of an attack that he's winding up does not mean it's being infused with Conq.
Which I'll show with a few scans below.
We didn't see him perform a conqueror's clash like Luffy did against Doflamingo to argue that he used regular CoC
It's not just clashes.
It happens regularly in Luffy vs Kat, two basic conq users winding up hits with red lightning coating their limbs.
Here he's winding up a Buso punch, but bc he's a conq, we see red lightning surrounding said punch
Same with Luffy here
Same from Kat here from a distance bc he's using a Mochi Donut to convey the hit.
Kaido has even used A-Conq in purple before.
Even Zoro's first conq showcase had 0 lightning bc Oda wanted to build up the reveal through Kaido's words.
Sometimes Oda follows what we expect, and sometimes he doesn't, based on the circumstances.
And if we say, "Well, this instance with Kaido was just because Oda hadn't fully worked out how he wanted to visually depict Adv Conq universally by then"
You could say the same thing for how BB uses the Gura Gura in tandem with Haki in general rather than Conq at all.
But yeah, I'm not sure if I'd even call it consistent since we have story instances of red lightning being present for regular conquerors outside of just while their haki clashes, and instances where A-Conq is used without red lightning at all.
possibly basic conq could still work tho ig.