It would be nice if Active Case would allow configuration of statuses that the user were allowed to set or change.  I don't own this module, but as a AC user through the support here, there are cases I have that I would like to be able to close myself.  I realize that you may not want the user to be able to change any status to any other status, so perhaps some relatinship configuration needs to be created to allow this.  Something like if the status is this, it can be changed to one of these.  If it is this, it can be changed to one of these others, etc.