I agree about the anything "non Jewish" or "anti Jewish" is automatically seen as antisemetism which is frustrating, and I can see DD's point that they seem to think they were the only victims, or at least have a HUGE chip on their shoulder. With that I'm 100% in agreement.
However, I don't agree that these places should be torn down. They are an important lessons to us and if anyone has ever visited the mass burial grounds, gassing chambers and war trenches it's a very humbling and saddening experience. They are symbols of our dark times and should be kept to remind us never to let these things happen again. Clearly we're not learning from our lessons seeing the attrocities that keep happening around the world - however they teach us a lot and are poignant memories that shouldn't be swept under the carpet.
The act of the theft itself is a callous act, however as platypus mentioned, no one shows outrage towards churches and other holy grounds being desecrated. It is sad that the thief seemingly had no respect of what that represents, sure it's only a sign, but for many unfortunate people it was the last sign they ever saw.
Please don't misunderstand my post, I'm not in any way condoning it's theft, I am just trying to show a less emotional response to the issue.