I don't see what the problem is here.
As you yourself say, no one is excluded, everyone is welcomed to play the game, everyone is involved, perhaps more so in Aurvandil than most realms due to the way the government works, and the vast wealth of current potential titles at the moment. So what is the problem? Some might not be included to out of game communication? Count me into that, I never post on the forum, and I don't intend to play the game by the forum, or find my gameplay subject to the hearsay of a few players on the forum. Have you even identified who is in this clan? Or if there even is a Clan? I've pointed this out before, if there is a clan, I don't know about them, if there is a clan, they aren't running Aurvandil, if there is a clan, they they don't override any In character processes.
If the problem is "but some players are losing, blaming it on a clan and then leaving the game" well tough, losers are losers, but if you start randomly deporting and placing arbitrary restrictions on players for what is hearsay on the forum, well then you'll lose players who aren't just upset because they lost the war. Why should I play Battlemaster, if some moaning on the forum is sufficient to see my characters deported, the realm I built from scratch dissolved and permanent restrictions placed upon me, and to what, mollycoddle some one? I won't play Battlemaster as a forum game, I won't play Battlemaster as an Out of Character game, and I won't accept a trial by forum, I sent you a long email and thoroughly explained the Aurvandil situation, I invited other players of my realm to do the same, if you can't even substantiate claims that there is a clan, and the most you can say is some players are frustrated that a realm is winning, and declare it a clan, well then it should be pretty obvious how this game is devolving in thanks to the forum enabling this.
Aurvandil isn't a clan, never has been, never will be, if there is a clan in Aurvandil, good for them but I still rule Aurvandil on my own, and I still ensure that everything is run in character and through the necessary channels, and that everyone is included, everyone is given fair opportunity and the out of game takes no precedence, and if there is any breach of that, I have the Out of character ban, sadly you can't ban the forum for trying to circumvent all in character events, happenings and its attempt to override gameplay.
