Because the author is pushing a race agenda and all his work is selective history that only fits his agenda.It's not in the WW1 section of the book. It could be hiding elsewhere, but I'd be surprised.
Why don't you read the book yourself and come to your own conclusions? It bothers you enough to post about it, so you could check it out?
Audible do a free book cancel within 30 days, if you're not already a member.
I wouldn't bother reading it.