Much of the policy around classified materials is designed to be idiot proof. I imagine the process for releasing the document was something along the lines of:

Much of the policy around classified materials is designed to be idiot proof. I imagine the process for releasing the document was something along the lines of: go into secure room; print out redacted document; review redacted document; take redacted document to non-secure scanner; release scanned version. Sending digital files across a security boundary is just a much more dangerous operation in general than sending paper. Given the prevelence and quality of OCR (particuarly when run on a good quality print, as was in this case), there is just not enough of a reason to take the risks of sending files across the boundary. EDIT: Idiot proof is probably not a fair characterization either. The other part of security policies is to be genius proof. What if someone involved is trying to exfiltrate data. There is a lot more places for them to hide it if you give them a digital pathway out then if you make them take it out on pieces of paper that will be reviewed.