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?"

I can't find much information about him between the 1936 Olympics and his emigration to South Africa in 1948, so this is going to be a rather limited answer. However he did apparently represent Germany internationally until 1941, and played for the Berliner SC until 1944. So obviously he was in Germany throughout the war, though there is no mention of how he managed to do so without being persecuted, or how he fared in those years. It doesn't help that I can't read German, as I suspect there may be more information available in German sources, but this is about all I can find in English.