Author.php display profile for all types of users

You can try to catch the 404 template and redirect it to the author template which will usee the same template for all users even if they are subscribers (or any other which have zero posts) something like this:

function no_404_for_all_users($template) {
    global $wp_query;
    if( !is_author() && get_query_var('author') && (0 == $wp_query->posts->post) ) {
        return get_author_template();
    }
    return $template;
}

add_filter('404_template', 'no_404_for_all_users');