Whenever I read about 50-year-old government secrets being revealed, I wonder about all the things happening today we're not being told about -- that we'll learn about 50 years from today.
Looking at the Earthrise image, as another commenter pointed out, they didn't simply degrade the image, but they deliberately added vertical lines with differing brightness and gain, so it would appear that the film scanners on the Lunar Orbiter could scan only at a very low resolution.
To use an analogy: Suppose you request a secret document from the government under the Freedom of Information Act. They decide to give it to you, but they redact 99% of the material with black markers. Oh, but they also retype the entire document, without the blacked-out portions, so you think you received the whole thing. They even add staples, 3-hole punches, coffee cup stains, and creases to the paper before photocopying it. You get 1% of material, but you are convinced that you got the complete unaltered original.