Because the argument is that Versailles was self-defeating punishment of Germany like the "rescue" is self-defeating punishment of Greece. The 1953 debt forgiveness is not a "self-defeating punishment".

There are three stories about the euro crisis: the Republican story, the German story, and the truth. -- Paul Krugman

Actually, since this is Germany, it's more likely to be this book, which makes it look like Keynes stole his title from Tolstoy. And Gysi's assumption that other politicians had read it seems to be wrong.