If that doesn't do the job and block them from scraping the site, then let me know and please post the actual user-agent string shown in the logs and/or IP Address of the AppSpot application doing the scraping or any other information you have from the logs, all with in the TOS of course.
On 403-bad-domain-scraper-thief.php put:
<?php header('HTTP/1.1 403 Forbiden'); ?>
At the top of the page.
Then put your regular HTML with a notice in the <body> section of the page:
If you are visiting us from [stupid-thief.com], please understand they are stealing our content and if you came from Google it would be appreciated if you clicked back to the search page and clicked "block all results from this domain", then revisited us. [link]Click Here to Bookmark This Page[/link] (It will display correctly when you visit again, as long as you do not click a link from [stupid-thief.com])
If you would like to view this page without clicking back and blocking the site stealing our content, simply [a href="<?php echo 'http://www.yoursite.com.'$_SERVER['REQUEST_URI']; ?>]click here[/a] to reload this page and view the content.