Earlier quoted context omitted.
My understanding is that the German people generally are very wary of data being moved around and collected 'unnecessarily'. I think a ploy like this would only backfire on FB.
Yes, I'd second that. While there would no doubt be some sort of outrage from the users, I don't think it would be nearly as strong as suggested. Germans in general, and especially the more educated, tend to be very protective of their data protection rights. If FB attempted something like this, it would be torn to shreds by German media.
Indeed being German I can say this is true for Germany because of the experiences with two dictatorships on German ground in the 20th century - the last one ending only about 26 years ago. Many people living in the GDR that were under supervision by the Stasi (often without knowing) have read the Stasi file (if it exists) and know what details have been recorded about their lifes and what kind of kompromat could in principle be derived from it.