About defend against the seige. Large organizations are more and more difficult to attack each other, and it is easier for large organizations to destroy small organizations or loose players who are the majority of games. If there is no restriction on bullying, the weak players can't play, no matter when they start to play for a few days and then be destroyed. Then, the players of the big organization are bored after two months and most of them don't continue to play. The game will soon have dozens of people and hundreds of robots playing.
As far as I know, the first few worlds have started a lot of people for a month or two, and then few continue. Because the players who are friendly and enjoy the game can't get the relaxation and fun from the game, the cruel and bad players will feel bored and give up the game because no more people for them to bully.
Such a good game, only a few dozen people and hundreds of robots online every year will not be the purpose of your development of this game, is it?