Here's how I would prefer to see the function (not tested) -- I think it's more readable, what do you think?

```php
/**
 * Implements hook_form_FORM_ID_alter().
 *
 * Restricts comment form to just the current vsite's users.
 * Since only certain roles (and not anonymous) users may post comments,
 * This form would only ever appear to authorized roles.
 * But we still want to restrict comments to just the current vsite's users.
 */
function os_comments_form_comment_form_alter(&$form, &$form_state) {
  if (!module_exists('vsite')) {
    return;
  }

  $node = $form['#node'];

  if (!og_is_group_content_type('node', $node->type)) {
    // Not a group content.
    return;
  }

  $wrapper = entity_metadata_wrapper('node', $node);
  $gid = $wrapper->{OG_AUDIENCE_FIELD}[0]->value(array('identifier' => TRUE));
  if (og_is_member('node', $gid)) {
    return;
  }

  // Deny access to the form.
  $form['#access'] = FALSE;
}
```