Yes, that's because not just the carbon infused plastic, but the vertical parts of the molded tub for the battery. On molded chassis like that, there is a tiny amount of flex, but it can't be considered "active" like flex in a carbon plate, because there isn't enough to affect the way a chassis drives.
The flex in the stock TA06 chassis plate was kind of "wishy-washy" and really wasn't springy enough to improve performance.