I agree in general, but for "signing key material", there should be enough entropy and they have enough control over the format to make it very easy to detect.

I agree in general, but for "signing key material", there should be enough entropy and they have enough control over the format to make it very easy to detect. Plus, they are the ones who put the security of their system behind this detection, letting developers access the dump they believed to be redacted. Whether they made a massive mistake at the design or implementation phase doesn't really absolve them.