Considering that this kicks the player who sends the invite, I strongly encourage you to add a messageAll when the RTB pref is changed. Otherwise, people could join when it's disabled, not be notified of this, and then send a trust invite after it was enabled.
Also, tell the player why they were kicked ( %a.delete("You were kicked for sending trust invites."); ) instead of just kicking them
Or just remove the kicking, it seems rather unnecessary.