I don't see any issue with what he said really, if he just added... "until wheel slip is detected" at the end.
Except that's not all we get from VTM-4 Jeb.
There are 3 functional 'modes' of activation.
The first, already discussed by Speed is the "Lock Control" mode. We know what that does, and that it's limited to 1st/2nd/R gears & to 0-18MPH, with the amount of torque to rear wheels being reduced as 18MPH is approached (zero "Lock" to rear wheels after that... this is only the "Lock" function that ends at that speed).
The second is Limited Slip Differential or LSD mode. This is as Jeb alluded to; where differences in speed & acceleration between front & rear wheels triggers increasing levels of torque to rear wheels, depending on how much difference (front to rear) is detected.
The third is Vehicle Acceleration Torque Control or VATC mode.
THIS is what has been overlooked completely by the description in that "primer". This is when the amount of torque to be delivered to the rear wheels is calculated based on the acceleration of the vehicle, as is determined/calculated in the VTM-4 unit. This is a significant element of our VTM-4, and is always active & automatic. (I will admit I am curious how the VTM-4 unit senses/calculates acceleration)
So, if you are driving straight & flat on dry roads & at a constant speed (zero acceleration), then yes, a minimum amount of torque will be delivered to the rear wheels (which is zero). If you want to call that "essentially" FWD, then OK... but that is a very temporary & fleeting state. That is the only time when this "steady state" of no triggers for torque distribution exists; and VTM-4 is active even then, but just not sensing any "torque diversion" triggers. All other times the VTM-4 unit will be varying the amount of torque to the rear wheels based on the circumstances being sensed & calculated by the system. I will say it would be nice to see a chart showing just how much torque goes to the rear wheels under what conditions (quantified). The diagrams in the SM are only conceptual & without numbers.
Lastly, I agree with Speed's suggestion that the author was confusing VTM-4 with VTM-4 Lock-Mode. Otherwise I would question his comment that ".... the VTM-4 system cannot deliver power to the rear wheels for a long period."
Edit: 'Just saw the link to the Gary Flint VTM-4 Explanation..... thanks for that Jeb. Much more authoritative & complete.