I can see German being hesitant about giving Poles "minority" status.
Well, they are immigrants, not a native minority...
What about Poles walking over and offering polish language classes?
About "Ruhrpolen": /wiki/Ruhrpolen
Ruhrpolen ("Ruhr Poles") is a German umbrella term for Poles(including Silesians, Masurians  , Kashubians), who migrated to the rapidly-industrializing areas of the Ruhr Valley, mainly from former eastern territories of Germany (the Prussian provinces of Posen, (Upper) Silesia, and East and West Prussia.) This migration wave, known as the Ostflucht, began in the late 19th century, while the Ruhrpolen arrived around the 1870s.
"Ostflucht"- fleeing the East.
Masses of Poles immigrated into "mean, opressing" Prussia for economical reasons...still not a native minority.
*and there's a lot more to be said about the unjustice being done to Poles in Germany*
Oh crap! Why don't they just leave if they don't like it....
What a horrible country Germany is...as it was back then with Prussia, right? Well...the movements of Poles speak a different language!