Is there a way to send CakeResponse from blackhole callback - ajax

Question

I am trying to make the ajax request more user friendly. It is a scenario that using a token which can be reuse in a period of time. However in time that a user has inactive for a certain time and tried to use the form, user will observe that the ajax not working but donno why. What I'm gonna do here is to display the message.
Using my testing code, doing return new CakeResponse seems to be return true in blackhole and therefore the $result is true although the User edit should not be triggered
public function beforeFilter() {
$this->Security->blackHoleCallback = 'blackhole';
}
public function blackhole($type) {
if ($this->request->is('ajax')) {
$this->log('blackhole here','debug');
return new CakeResponse(array('body'=> json_encode(array('data'=>'The request has been blackholed')),'status'=>500));
}else{
$this->log('blackhole there','debug');
return new CakeResponse(array('body'=> json_encode(array('data'=>'The request has been blackholed')),'status'=>500));
}
}
in the userapp
public function edit() {
$userId=$this->Auth->user('id');
if (empty($this->request->data)) {
$this->request->data = $this->User->read(null, $userId);
}
if ($this->request->is('ajax')) {
if($result = $this->{$this->modelClass}->edit($userId, $this->request->data)){
$this->Session->write('Auth', $this->User->read(null, $userId));
return new CakeResponse(array('body'=> json_encode(array('data'=>'saved')),'status'=>200));
}else{
return new CakeResponse(array('body'=> json_encode(array('data'=>'error')),'status'=>500));
}
}
}
Progress 1:
Unsolved, perhaps needed to use event handler or exception, though it will be somehow complicated . Still thinking while refining other plugin feature.