Consumer Reports concerns itself with mainstream consumer products that are broadly available in the US. Their primary concern is testing advertising claims and evaluating big-ticket products.
Broadly available ebook readers, these days, means Kindle and Nook.
They are what they are; good at what they do but they don't try to do everything. They don't normally cover niche or specialty products you have to go out of your way to find. And they don't target hobbyist and enthusiast products which is what Mobileread is for.