Sure, your "explanation" is Luffy having a serious fight and randomly forgetting the highest level of offensive haki he had just acquired
.
All while saying he had no idea how to damage them no less. Super logical.

All while saying he had no idea how to damage them no less. Super logical.
Why does it burn that much Gaban saying even a skuplitter needs to be mindful about how he uses the CoC lol?
So again:
Luffy did use it in serious fights --> he could
Admirals didn't in non serious --> they couldn't
Perfect lol.
Luffy did use it in serious fights --> he could
Admirals didn't in non serious --> they couldn't
Perfect lol.
Gaban confirms ACoC is the counter to their immortality and Luffy received no training from Gaban. Admirals having CoC is confirmed literally nowhere and they've had ample opportunities to show it and still nothing, this isn't the "gotcha" moment you seem to think it is.
I don't mind repeating this back and forth, but know that you won't achieve anything.