Silvers could stop hiding in bronze, and try to get better fighting stronger enemies. That is what I did back when I started to play Apb, you won't get better by stomping on bronze players.
Or we could disable the server list so, we only can choose what district we want to play.
Or lock the threats again, and only make it possible to join other threats than your own. By choosing what district you want to play,
and if all the recommended servers are full then the game will pick anyone that has space. This would also make it possible, to play with friends who are not the same threat as yourself.