Extra Authors Redirect

PMF

Does this affect posts / pages / admin / ???

No. this only affects people going to the /author/ template page on a site, and only affects those that have been marked to redirect.

Can I change where the redirect goes?

Yes. There is a filter to change the default behavior. In your functions file, include the following:

function new_auth_url($location) {
    $location = 'http://google.com';
    return $location;
}
add_filter( 'extra_author_redirect_url', 'new_auth_url' );