That's definitely strange. Maybe just a typo in the Apex book?
I wonder what the in-game manual says. I read it earlier, but I don't remember. It would be easy enough to test in game though. Just take a car to practice, do full toe in drive it, see if it understeers a lot. Then toe it all the way out and see if you can drive in a straight line.
If it's backwards it should become apparent pretty quickly.