In Nazi Germany, maybe... Our perception of justice changed a bit since then, in case you haven't noticed.:IS2:Guilty until proven innocent...
Besides, it doesn't say every German soldier was a nazi. It says photos of people in uniforms of soldiers who fought for the nazis arguably carry a certain meaning.
What you should think of this, if you're using such photos in a mature manner, is that this is true and you consciously accept this but you decide to use the photos anyway because a) you need them for the purpose of role-playing and b) you trust yourself to not be a nazi and you trust others to see that, despite your use of this imagery.
You can't just turn a blind eye to it and ignore the implications because you don't like them!
I mean, of course you can. It's none of my business. But in my humble opinion, this doesn't constitute a mature use of the photos anymore and the "they weren't all nazis, you know?" rhetoric doesn't change that.