While it's probably true that the program left MUCH to be desired (it is, after all the History Channel) ... the film is being marketed as "Tom Cruise as a Nazi", so its the studio's own fault people have that (mis)impression.

And reality-wise, whether or not Stauffenberg etc. were truly members of the party, they were members of the government that was ruled by the party ... they were complicit, and that's what's important, more important than technicalities. Yes, members of the German Army were unhappy when Hitler became their commander, but they still fought the battles, didn't they? Don't actions speak louder? Their morality appeared as soon as the Allies would be victorious. If these generals knew there was something wrong, why didn't they make a stand earlier? They would have died, but they still could have. Which is exactly the reason July 20 didn't work out.

It was simply too little, too late.

On the other hand, I'm certain that the intellectual, non-military (or not higher-up) conspirators were likely fully committed to ending atrocities they knew about ... but they really had little to do with the attempts made on Hitler. They didn't have the proximity that the military did.