Retrieve user_meta and copy to post_meta

First of all get_users_of_blog has been deprecated, so you should use get_users instead, or run a WP_User_Query.

After that, the_author_meta echo the meta value, not return anything. To return the meta you should use get_the_author_meta()

$blogusers = get_users( $args ); // for args see codex

if ($blogusers) {
  foreach ( $blogusers as $bloguser ) {
    $user_location = get_the_author_meta('geo_address', $bloguser->ID );
    $has_meta = get_post_meta(463, 'geo_move', true);
    if ($user_location && ! $has_meta) add_post_meta( 463, 'geo_move', $user_location);
  }
}