I know that, I follow the Anime too. :yeah:
Plus, because it was a filler, you know this as well, it makes it non-canon. So, it doesn't really matter how convincing and interesting was, cuz it was never real.
That's a very narrow-sighted view on things. It was published under the Naruto name and Kishi has stated he is a fan of the
official anime and supports it. Using the manga as a bible shouldn't be a thing and you can assume that Kishi just never had the panel space to say something like 'oh hey danzo bodyguard #2? oh yeah you are shinos adopted brother here's some random flashback' because that obviously would be out of the blue.
Non-canon is a term only used for VS matches and matching character's feats. You can't argue that Kabuto could beat ninja A because he can make another 9tails (Like he did in Chikara) because that obviously is different. Connections and stuff like this though, totally plausible.
Anything that doesn't contradict the existing source material like Torune and Shino knowing each other could've easily actually happened in the Naruto manga, theres no proof that it didn't. You can tell Kishi is fine with whatever minor changes they make to his universe because otherwise he'd change something. It's just adding more to the world and Naruto is Naruto.