Comment by mpyne

Oh, there's tons of much better methods that would be more than good enough. Adobe even provides specific redaction features that drill down within the PDF data itself to make sure that nothing gets drawn under a redaction block, it works quite well.

But the government is about making procedures that are both easily understood by low-paid civil servants and unlikely to be screwed up in major fashion (e.g. our GS-7 scanning documents back in might use the wrong file name or reverse the pages or something, but they probably won't leak classified data if they do that).