Kaido "killed" Orochi.
Shinobu informs the readers that he wasn't the main goal in the first place. The one who needs to be taken down is Kaido.
They failed and Oda decides hmm so I couldn't write them to beat Kaido so I will bring back Orochi so they can have their winning moment.
This is a bad writing decision after what he established with Shinobu. If he didn't make her say that. The situation would be hella different because everyone would know that Scabbards will fight Orochi if anything.