Yeah all the same permissions in editpost.php still apply.

If you want the quick edit button to be invisible to unregistered posters just use this code in admin/functions.php instead of the code you added from the instructions.
Code:
if ($post[username] == $bbuserinfo[username] and $bbuserinfo[userid] !=0) {
$edittext = htmlspecialchars($post[pagetext]);
eval("\$quickedit = \"".gettemplate('showthread_quickedit')."\";");
} else {
$edittext="";
$quickedit="";
}