Change field settings based on role (for admin only)?

I think I've figured out how to target the field's widget, and to do this based on the admin role, but the module doesn't seem to be recognizing the widget type for some reason. The reason I say this is that when the module is enabled, the targeted field disappears in the node edit form. I figure this means it's getting targeted correctly, but can't define how to display itself. I think this might be because the autocomplete widget is defined by the Entity Reference module itself, and not by Core. Do I have to tell the module where to find this widget type? Or is there another reason that this might be happening?

    <?php

    //Assign role that will be affected by the module
    if(user_access('administer')) {
      function entityreference_widget_field_widget_properties_alter(&$widget, $context) {
        // Change entityreference widget 
        $field = $context['field'];
        if ($context['entity_type'] == 'node' && $field['field_name'] == 'field_review_band') {
          $widget['type'] = 'entityreference_autocomplete';
        }
      }
    }

So, I've figured out part of the issue, and have been able to change the widget from a select list into an auto complete field. However, the issue still exists that admins are only allowed to enter values that exist in the original select list. This is because the only allowed options are still the admins' own bands, from the view that populates the options in the select list. I now need to figure out how to alter the settings for the field.

I have been unsuccessfully working on this for hours, because I'm not sure what elements to target. I've tried altering the settings through $form_state using hook_form_alter, which apparently doesn't work because $form_state is called after submission or something like that, thereby removing the altered settings. My latest attempt is below, through hook_field_widget_properties_alter. But, no matter what I try, I can't get these settings to stick. I'm guessing it's because you can't directly alter $context or something.

If anybody has any suggestions, I'd really appreciate some help. Latest attempt:

function entityreference_widget_field_widget_properties_alter(&$widget, $context) {
  //Assign role that will be affected by the module
  global $user;
  if (in_array('administrator', $user->roles)) { 
   
    // Alter entityreference widget
    $field = $context['field'];
    dpm($field['field_name']);
    dpm($widget); 
    if ($context['entity_type'] == 'node' && $field['field_name'] == 'field_review_band') { 
     
      //Change widget type
      $widget['type'] = 'entityreference_autocomplete';
      $widget['module'] = 'entityreference';
      $widget['settings']['match_operator'] = 'CONTAINS';
      $widget['settings']['size'] = '60';
      
      //Change widget settings
      $context['field']['settings']['handler'] = 'base';
      $context['field']['settings']['handler_settings'] = array(
        'target_bundles' => array (
          'band' => 'band'
          ),
        'sort' => array(  
          'type' => 'none',
          'property' => 'nid',
          'field' => 'body:value',
          'direction' => 'ASC'
          ),
        'behaviors' => array(
          'views-select-list' => array(
            'status' => '0',
            ),
          'test_field_behavior' => array(
            'status' => '0',
            'test_field' => '0'
            ),
          ),
        ); 
    }
  }
}