Set order / weight of user profile core fields against user profile custom fields
You can just try and set the weight as follows

$form['status']['#weight'] = field_info_max_weight('user', 'user', 'form') + 10;


Have not tried it but I am pretty sure it will work. This will make sure the status will always be the last field.

Also it should be $form['account']['status']['#weight']