I think you failed to read or understand the second part of the response.
These bonds are backed by the “Full Faith and Credit of the GERMAN government.”
In the words of our beloved leader, Greece is “Too Big To Fail”. If the deluded dream of the Euro is to survive, Greece will have to be bailed out. And the only one that can pay the bill is GERMANY.
So it actually not a bad play. Get the high interest rate and in a default, the Germans will pay the note off.
What’s stupid about that?
If the risk/return ratio meets your criteria, then go ahead and invest. I sold my national debt securities in 2008 and 2009 and have avoided significant losses. The economic theory in play is that when governments think they can get a bail out, then they are less willing to face up to fiscal reality. The choices they make with other people's money is different than the choices they will make with their own money. Nations such as Greece that think they can be bailed out will not make the internal changes necessary to put their economy back on track.
I am not arguing from a conservative ideology point of view. I am arguing from an economic standpoint.