Well, the fact that you messed up the first time (uploading a copyrighted file without permission) grants them every right to ban you personally. The fact that they ban people who use your internet is also ok, because they need to make sure it's not you with another account. I'm sure that if you send a personal email to the owner of the website (Nicolas) with all your explaniations (and your approval emails from the authors of the original aircraft, which for some reason you still haven't shown us) he might let you re-join, but that is highly unlikely after what you posted on your "blog".