Even if it was a "Setting book" it is bad at that too.
Do I get a region of space to play in with details about worlds and such? No. That's in a completely different, non 5FW book. Do I get rules or advice on adapting that other book to the specifics of this particular paradigm? No.
Do I get a new way to play or a area that is optimized for a type of game play that isn't normally feasible? No. Because it doesn't change anything about the Spinward Marches. By your own admission, it doesn't help you run military games or help with running your non military games in a warzone.
This book says "hey, imagine a war. Here's some arrows on maps." It does not do anything for gameplay, either as a campaign or as a "Setting". It was fun to read, but it is not remotely useful for gameplay.
I am complaining that this series is, once again, totally unhelpful for actual play. I lived through GDW's 5FW and their Rebellion and this is more of the same disregard for use that those books had. Maybe the books coming will redeem it, the way Hard Times almost did with the Rebellion. We'll see.
I am not complaining that an Orange isn't an apple. I'm complaining that it is neither an orange OR an apple, it's a Still Life.