I wouldn't say anti-Nazi org, but rather just a place that is, for better or worse, trying to bury their Nazi past.

You can interpret it in two ways, I guess. One is trying to move beyond that horrific past by outlawing Nazi symbols, and they refuse to make exceptions so as not to give the Nazis any ground.

But on the other hand, refusal to allow such images to be used for a film specifically set during that period of time can also be interpreted as denial that the place even had a Nazi past at all.

If the joke is that they are shocked and defeated by the promise of using real historical footage depicting their actual Nazi past, it implies the latter interpretation being the more correct, since any place that is truly remorseful about the past wouldn't try to deny what happened and therefore wouldn't take offense to the use of historical footage.