More accurately his work was raped by the Nazis. It didn’t quite fit the narrative Hitler was pushing. It had to be censored to pass muster in Nazi Germany.
You may want to read Paul Lawrence Rose’s “Wagner: Race and Revolution” - http://www.amazon.com/Wagner-Revolution-Paul-Lawrence-Rose/dp/0300067453 that clearly shows Wagner’s Proto Nazi ideas. Hitler was friends with the Wagner family. The propaganda after the war and the holocaust is pretty thick by those wishing to defend Wagner from Nazism.