Now you're assuming that kaido is the one who first called her devilfruit the guardian diety of wano rather than it being information that he learned and relayed. It's possible that is just a common term used at different times yet these guardian deities are all zoan type which have been said to have wills of their own.
Nothing you've said has any logic or rational thought behind it, it's like you're only able to comprehend the information at face value. If you're going to try and discredit what someone is saying, it's best that you're able to understand what is being said first.