Luffy mastered adv CoA , why his ass couldn't move faster and block hakai using barrier haki ? all of what you type since the beginning are some hard headcanons and cope ; all of what u got is just excuses that even some users here calling u an alt of someone , foh Zoro on panel moved faster than them all , Luffy has the same thing that Zoro has and could do the same thing that Zoro did but his ass was slower despite perceiving the attack let's not talk about Law
Luffy used haki under water
Luffy is a CoO user , tf u mean dropped his guard ; Luffy was dropping his guard in FMI and could perceive that someone was attacking shirahochi ; that's CoO WORK clown ; it helps u at reacting either dropping ur guard or not
Crazy how u didn't provide a single point ; and all of them are excuses