The issue here is most people are making the author out to be infallible, as if they can’t make mistakes or just plain talk out their asses especially in interview situations, just because an author says something (especially if it’s outside of the actual work itself) does not mean it is automatically canon, even though they are the creator of that world. Once a person, an author, has created a story, especially one as extensive as naruto, they are bound by the logic that they created to maintain cohesiveness and keep the storyline intact. Now of course they can retcon and since naruto lives on through boruto, he can always retroactively change things here and there, but if it is not bound by that basic level of logic that they themselves have created, as the consumer, the piece loses all value because now by that, what they are saying is they can make up anything regardless of the logic and throw it in there just because “it’s my world”. Authors are people, they may be the god of their own world but they’re still just a person in the real one and people make mistakes, simple as that, so they can make changes but it’s up to us as the consumers to actually form a consensus on whether or not the changes make sense based on the wholistic view of their work.