I think the way the 'default value' works is sorta incorrect. Except for a required nature.
We need a bit more language, however.
$value = $row['default_value'];
//$value = $row['default_value'];
$value = '';
Let's users select the blank box again. And it works, but it does make the profile look weird on refresh. If you then go somewhere else, come back to profile view, it shows everything as it should.
Is there an if required check ?