I think it would be neat to create a restraining order plugin. This would allow admins to create restraining orders between players, so player x can't move withen x blocks of player y. eg. one could do /restrain player1 player2 r:300
This could be a good plugin, but what about if a player sits in an important place? Like if they are at spawn that other player would not be able to use spawn.
Maybe set it up to work with world-guard so that the restraining order does not apply when the players are in a certain region. Maybe something like this could be a command: /restrain player1 player2 r:300 -wg:spawn