I don't think it's a moot point. Put the admin functions in their respective controllers (ie, not all together in one 'admin' controller), and use 'admin' prefix routing, built into Cake, to keep them secure. This is the CakePHP sanctioned way to do it, and CakePHP allows you to create admin functions in this way via the Bake console.
You can protect all controller functions prefixed by admin_ with a few simple lines of code in your AppController, and all admin functions can be accessed via tidy, consistent URLs like this: http://www.example.com/admin/my_controller/my_function
This should get you started: http://book.cakephp.org/2.0/en/development/routing.html#prefix-routing
Let me know if you need more help and I'll update my answer with more info.
EDIT: More info...
Here's some steps to set up admin routing:
1/ in app/Config/core.php, around line 113, make sure this line exists and is uncommented:
Configure::write('Routing.prefixes', array('admin'));
2/ In app/Controller/AppController.php (ie, the controller superclass), test for admin routing in your beforeFilter method. Do NOT do this in the beforeFilter of each controller - that is not in tune with DRY principles. Here's my before filter method as an example:
function beforeFilter() {
if (isset($this->request->params['admin'])) {
// the user has accessed an admin function, so handle it accordingly.
$this->layout = 'admin';
$this->Auth->loginRedirect = array('controller'=>'users','action'=>'index');
$this->Auth->allow('login');
} else {
// the user has accessed a NON-admin function, so handle it accordingly.
$this->Auth->allow();
}
}
3/ Prefix all your admin functions with admin_ and they should automatically be available via prefix routing.
eg.
function admin_dostuff () { echo 'hi from the admin function'; } // This will be available via http://www.example.com/admin/my_controller/dostuff
function dostuff () { echo 'hi from the NON-admin function'; } // This will be available via http://www.example.com/my_controller/dostuff
Once you've got that set up, all you need to do is prefix admin functions with admin_, and Cake will handle it all for you. Make sense?
EDIT 2:
Here's some quickly-written example code that should help your situation.
function beforeFilter() {
if (isset($this->request->params['admin'])) {
// the user has accessed an admin_ function, so check if they are an admin.
if ($this->Auth->user('user_type') == 1){
// an Admin user has accessed an admin function. We can always allow that.
$this->Auth->allow();
} else {
// A non-admin user has accessed an admin function, so we shouldn't allow it.
// Here you can redirect them, or give an error message, or something
}
} else {
// the user has accessed a NON-admin function, so handle it however you want.
$this->Auth->allow(); // this example gives public access to all non-admin functions.
}
}