#access setting not working in #after_build

Setting '#access' = FALSE in #after_build, only hides the element, it does not protect it from being posted. End user is still able to post data, i.e. manually alter the client-side code, insert <input type="text" id="edit-path-alias" name="path[alias]" value="" size="60" maxlength="255" class="form-text"> and post data.

Example:
The code below, sets Path Alias #access to FALSE, yet you're still able to post Path Alias by altering client-side code.

<?php
function mymodule_form_alter(&$form, &$form_state){
  if (empty($form['type']['#value'])) return;
  $form['#after_build'][] = 'mymodule_after_built';
}

function mymodule_after_built($form, &$form_state) {
  $form['path']['#access'] = FALSE;
   return ($form);
}