I’m rewatching the anime right now, and it’s at the part where Orochi is talking to CP-0.
At first, I thought that Akainu might not know anything about what they’re talking about, but then I realized something: What if he does?
I don’t think Akainu will ever admit it to his men, but I think Akainu knows the World Government is buying weapons from Wano. I mean with all of the arsenal and weaponry the Marines have, he’s gotta have some idea of where that comes from.
So Akainu is scared of attacking Wano because if he does, they’ll no longer have any place to get weaponry from. And it’s just my hunch, but I feel like the World Government isn’t just getting normal weapons from Wano – but weaponry using Seastone.
So the Marines will never attack Kaido because they NEED him since he, Wano and Orochi are in business with the World Government.
*Theory by Tatlo