Having a style that is reminiscent of another artist is not "plagiarism." It's having as style that is reminiscent of someone else. And let's not forget—this other artist (and presumably all the artists in this "contest") are doing work in the "Disney-style
," so I guess that makes them ALL "plagiarists" by their own standard, right?
It looks to me that you got good at drawing in this "style" and that's what's freaking them out. You can back up all your claims with proof (your offer to draw something on video was a good move—it's hard to fake that) and they don't want to hear it. I think they just don't want to admit that you're good and that they were wrong in accusing you. So better to just give ineffectual claims of "you just don't get it" rather than retract what they initially said about you.
If Kamirah is on deviantart, why don't you just send her a PM yourself through dA? She can post something on her dA blog if she is inclined.
It's a shame that you have to deal with such small-minded people. You have a lot of talent and skill. I foresee you using this skill in many other artistic applications in the future, so the last laugh will be on you!
P.S. I just found Kamirah on dA. She seems approachable to me. I say, contact her yourself.
P.P.S. I understand that doing fan art is fun (and I've done my share of fan art too, so I'm not saying I'm "above" it) but let's be honest here. These people are all FULL OF IT. You all
are doing derivative work in the "Disney" style. They need to get over themselves and stop dragging down someone (you) who has cultivated some drawing skill. I am sure I won't be the first to encourage you to branch out and do other types and styles of drawing (you are very good!) because then you won't have to deal with closed-minded freak idiots who will accuse you of this kind of nonsense. Some of the fan art subcultures (like manga, cartooning fan art, and others) are populated by a certain amount of nutcases. Who needs to deal with this?