I haven't researched this.
My guess is that a full scan of the book would be an affront to the powers that be. Partial scans used solely in a non-profit context for fan criticism would seem to be appropriate to me... but may still infringe on a legal agreement somewhere.
I don't believe the journal is technically a published work. Meaning that I don't think copies were submitted to the Library of Congress. I think it's meant to be a fictitious "replica", or simply "merchandise" and not really a "book". I may be wrong about this. I don't recall seeing a copyright notice anywhere on it.
One could argue that the entire perceived value of the item- apparent by its marketing- was its potential ability to explain "mysteries of the Halo universe"; therefore, the producers of the item expected their large, intenet-enabled fan base (we, the consumers) to pick it apart page-by-page.
And that we can, by citing page numbers and providing our observations. But to do that you have to have a copy of your own.