There's only one thing I grade non-fiction on. Does it teach?

This does. It doesn't teach the most accurate information. It's sensationalist; starting-facts exaggerated enough to cross the line into 'wrong' sometimes. However because the author is not an expert, that not only works, but may in fact be the correct thing for a modern & moral person to do in this day & age. 

At its core, this book is an ammo-can. It may not appeal to a group outside an echo-box, but it excels at arming those in that group for some family debates.