I will explain the definition of a fantard. "Fantard" is a combination of the words "Fan" and "Retard". It's okay to be a fan but, not really to be a fantard. Fans(By which I mean normal fans) understand the fact there are people who don't like what they like and don't attack people for their opinions even if they don't like what they like. Fantards are the obsessive fans who hate the fact that there are people who don't like what they like and they attack people for their opinions and the only people they don't attack are the ones they agree with.
But... Uh. Naruto's sexuality is never discussed in detail in the anime--it is covered early on as a 12 year old that he likes Sakura, and nobody really knows much about their sexuality at 12... So, you can't realize something that is never really covered.
Most anime characters are bi--they are whatever whomever wants them to be, specifically because manga-ka know that there are gonna be fans of every type of pairing.
Especially manga-ka like Kishimoto-sama or Takahashi-sama.
It distresses me mildly that your idea of responsibility relies solely on the fact that someone must agree with you. While I do not necessarily believe either way as I only read Naruto to look at the character concepts, it's not really fair to decide that your way is the only way anyone can ever interpret and be considered responsible... isn't it?
I speak about the manga, not the anime. The American anime has not reached Shippuden yet. After the time-skip it becomes much more apparent that Naruto loves (Yes, loves) Sakura and while he cares about Sauske (and his other friend-boys) it is in a completely non-romantic way.
And I honestly think my way is responsible, so why should I not say it? I don't want people to contort the characters I love into something (or someone) unrecognizable! If I were a manga-ka, (and I do have many original characters and a comic of my own) I would not want someone to mess with my characters. In the comic I draw, there are two male characters. And if someone gets the dumb idea to try and pair them up, when it is OBVIOUS (or going to be. It will be soon) that one of them is in a relationship WITH A WOMAN. AND HE IS TOTALLY STRAIGHT I would be very... angry. =/
I just think it's more responsible to respect the manga-ka's wishes. While Naruto's sexuality has not been touched on in the anime yet, that means you can't say he's gay/bi either. =/
I don't want to start DA drama, but I will say this:
Thinking that you have full reign over the characters and that you can do what you wish with them is wrong. They are not your puppets. They may not be real, but somewhere, somehow, someone thinks they're ... people. They have dislikes and likes and shit... they have character. Just like anyone.
I'm not saying that her way is the only way, but her way is the way that makes sense - to me. I realize that these characters arn't my puppets to contort in any way I see fit, and I think it's a dishonor to the manga-ka and the manga ITSELF to believe I have that sort of power. I don't. You don't. No one does.