DSC operates on any (or all ) wheels that are losing traction in addition to backing off the throttle, hence the four channel ABS on the D3
It is not 'per axle' -this would futher amplify any instability... sounds like he's talking out of his @rse

Quote:

ABS
ABS controls the speed of all road wheels to ensure
optimum wheel slip when braking at the adhesion limit.
This prevents the wheels from locking, which helps to
retain effective steering control of the vehicle.
On the front axle, the brake pressure is modulated
separately for each wheel. On the rear axle, brake
pressure is modulated by select low. Select low applies
the same pressure to both rear brakes, with the pressure
level being determined by the wheel on the lower
friction surface. This maintains rear stability on split
friction surfaces.
CBC
CBC influences the brake pressures, below the DSC
and ABS thresholds, to counteract the yawing moment
produced when braking in a corner. CBC produces a
correction torque by limiting the brake pressure on one
side of the vehicle.
DSC
DSC uses the brakes and powertrain torque control to
help maintain the lateral stability of the vehicle. While
the ignition is on the DSC function is permanently
enabled unless selected off by the DSC switch. Even if
DSC is deselected, driving manoeuvres with extreme
yaw or lateral acceleration may trigger DSC activity to
assist vehicle stability.
DSC enhances driving safety in abrupt manoeuvres and
in understeer or oversteer situations which may occur
in a bend. The ABS module monitors the yaw rate and
lateral acceleration of the vehicle, and the steering input,
then selectively applies individual brakes and signals
for powertrain torque adjustments to reduce understeer
or oversteer.
In general: in an understeering situation, the inner
wheels are braked to counteract the yaw movement
towards the outer edge of the bend; in an oversteering
situation, the outer wheels are braked to prevent the rear
end of the vehicle from pushing towards the outer edge
of the bend.
The ABS module monitors the tracking stability of the
vehicle using inputs from the wheel speed sensors, the
steering angle sensor and the yaw rate and lateral
acceleration sensor. The tracking stability is compared
with stored target data and, whenever the tracking
stability deviates from the target data, the ABS module
intervenes by applying the appropriate brakes. On
vehicles with an automatic transmission, when the DSC
function is active, the ABS module also signals the
Transmission Control Module (TCM) to prevent gear
shifts. If necessary, the ABS module also signals:
• The ECM, to reduce engine torque.
• The transfer box control module, to adjust the
locking torque of the center differential.
• The rear differential control module, to adjust the
locking torque of the rear differential.
The DSC function overrides the differential locking
torque requests from the terrain response system.