We have seen Harald using CoC multiple times in the past, why now was necessary to show it? As said, even Rocks didn't in most instaces.
Also, I am only saying that if you apply this very same method to Kaido vs Oden, at what consequences do you get?
In this very same chapter, Imu tells no one could have killed Harald. And at this time we were far after GV.
Just to say one.
Because Oda mention stuff when he thinks it's important.
Yeah we see harald use CoC in past same over and over same for Rocks and Grap and Roger .
Still in DR rocks fight Oda made sure to mention rocks using CoC defence because it was a very important aspect of the fight .
This also tell us how to get around that by using load of haki and show us it disable DR .
That was not possible with harald the out come of fight had to be differnt for story reason .
Oda could also let loki kill harald while he was going all out like how roger and grap had to do to rocks but that was not point .
So he let harald get back his mind so loki can get killing blow without have him fighting back at all .
Yes imu say he think no one could killed harald but don't mean h ecan't be wrong .
Plus i don't think Imu just expect harald to let him self get kill .
Imu also say 39 year ago that davy and joyboy would never return but both of them are in there own way .
Character say stuff that is be wrong all the time .