I'm beginning to think that the amazon.com group that edits/checks book reviews before releasing them out to the public site have a liberal bias of their own.
The other day Freeper Grundle's book review of "The Skeptical Environmentalist" took many days to appear on the product page listing, while many liberal leaning reviews scooted through to the page even though they were posted days after Grundle's review.
Just a theory, at this point, but worth watching.
Regarding your theory: Interesting that I once posted a respectful and glowing review of Dr. James Dobson's book - to counter all the liberals who'd posted hate-filled invective calling him cruel and heartless (for advocating corporal punishment under certain circumstances).
My review was NEVER even posted. I've wondered ever since.