Drupal7: JSON, hook_form_alter & hook_menu

<?php/** * @file *  * @author DrupalD *//** * Implementation of hook_menu *  * @author DrupalD */function siteinfo_tweaks_menu() {    $item = array();    $item['JSON/%/%node'] = array(        'type' => MENU_CALLBACK,        'page callback' => 'siteinfo_api_data',        'page arguments' => array(1, 2),        'access callback' => TRUE,    );        return $item;}/** * Impementation of hook_form_alter * @param Array $form * @param Array $form_state * @param String $form_id * @author DrupalD  */function siteinfo_tweaks_form_alter(&$form, &$form_state, $form_id) {     switch ($form_id) {        case 'system_site_information_settings':                        $siteAPI_key = variable_get('siteapikey', '');            //If site API key is set, change the value of the submit button            if ($siteAPI_key != '' ) {                $form['actions']['submit']['#value'] = t('Update configuration');            }                        //Add site API field            $form['siteinfo_api'] = array(              '#type' => 'fieldset',              '#title' => t('API'),            );                        $form['siteinfo_api']['siteapikey'] = array(              '#type' => 'textfield',              '#title' => t('Site API Key'),              '#description' => t('Provide the API key'),              '#attributes' => array('placeholder' =>  t('No API Key saved yet')),              '#default_value' => variable_get('siteapikey', ''),            );                        //Add a submit routine to display custom message            $form['#submit'][1] = 'siteinfo_tweaks_submit';            break;    }}/** * siteinfo_tweaks_submit *  * Custom submit routine *  * @param unknown $form * @param unknown $form_values * @author DrupalD */function siteinfo_tweaks_submit($form, $form_values) {    $siteAPI_key = $form_values['values'] ['siteapikey'];    drupal_set_message(t('Site API Key has been saved:  @api', array('@api' => $siteAPI_key)));}/** * siteinfo_api_data *  * Return API key in JSON format *  * @param unknown $siteAPI_key * @param unknown $nid * @author DrupalD */function siteinfo_api_data($siteAPI_key, $node) {    //Make sure the API key is present & its the one which has been saved previously    if (variable_get('siteapikey') != '' && variable_get('siteapikey') == $siteAPI_key && $node->type == 'page') {        return  drupal_json_output(array('node' => $node));    }    else {        drupal_access_denied();    }}?>