So what?
Law knew, that Kaido was in Wano.
Doflamingo knew, that kaido was in Wano.
BM knew, that Kaido was in Wano.
The marines knew, that Kaido was in Wano.
It took the SHs one day in the New World to learn that Kaido was in Wano.
Basically the entire fecking world knew that Kaido was in Wano.
And here Oda is trying to sell us that WB - most influential man on the world seas - didn't know that Kaido took over Wano.
That's ridiculous and simply very lazy writing.