Its fine that it's canon.... I have no reason to refute it or debate over it. I'm just saying that if it was so important and pivotal to the main plot of the story it would
probably also be explained in the manga directly.
For example, how knock up streams work and how the cumuloregalis cloud is able to support structures was explained directly in the story so even someone like me who isn't exposed to SBS and the like still know about it. Since those kinds of things don't exist in this world, suddenly being expected to believe that there's an island floating in the sky would be hard for a reader to believe without an explanation (which is why I believe it was explicitly explained in the manga as important to make the story believable). But since I don't keep up with stuff outside the manga and anime, I don't expect most people to know those details like the Super-floating wood.
But if a situation ever came up where people would debate over "why did the wood not sink when it should've?" then this little tidbit about the super-floating wood would be important and the fact that it's canon with regards to the story even though it wasn't stated in the manga would
also be important.... until that happens though, (I think) it's not really that important for everybody who keeps up with the story to know.
EDIT: Actually, if you're talking about the floating wood the strawhats used to rise out into the new world, I was already satisfied (as a reader) with the explanation that Franky gave
here in the manga.