Rudi Ball, a German Jewish hockey star that played on the German national hockey team during the winter olympics in '36 allegedly struck a deal to play in exchange for his family's safety. Did he, an open Jew, really stay in Germany throughout WWII?

I'm taking all of my information from wikipedia, so first thing first: Did Rudi stay in Germany throughout the war? Were there other openly Jewish Germans hanging around in Germany during the war? If so, what was the Nazi justification for this... the 30's version of "s/he's one of the good ones?"