This is worth nothing.
I refer you to Greg's comments on Vivre Card and other editorial stuff.
Oda approves but doesn't read/fact check these things.
So One Piece Manga, Vivre Cards, Databooks, SBS, Volume Cover all call Kaidou the Strongest by accident or by mistake, eh?
If it's one or two sources giving contradictory information, you have a point.
But literally every OP material about Kaidou calls him WSC lmao.
If all of them are wrong... what is Oda checking then?