The problem you are having here is that standard is not a post format. standard is just assigned to posts that does not have a post format assigned to it. You can also check in your db in wp_terms, there is no post-format-standard term. You can also do the following to print out a list of all registered post formats
$terms = get_terms('post_format','hide_empty=0');
?><pre><?php var_dump($terms); ?></pre><?php
This is actually one flaw in the post format system. I don’t know if this was done on purpose. Unfortunately, you can’t add new post formats. So you can’t register a standard post format. You will need to go and rethink your setup when adding a meta box for posts that does not have a post format assigned to it