Don't try to think of tires in terms of static and dynamic friction. Under applied torque there's also some non-zero amount of slip (ratio).
But yea, you want to prevent lockup since peak braking potential is before that point. Tires will tend to make more grip when they're under slip than when they're totally sliding.
With equal brakes left and right, you inevitably lock up the inside before the outside due to load difference. Inside can't sustain as much torque.
Idea of that viscous coupling on the front is..
- Allow a small difference in LF and RF wheel speed without any "lock" so you don't have un-necessary understeer during normal cornering, when the difference in wheel speeds are close
- After you exceed a certain limit (the "deadband" they mention), like when the inside is about to lock up and is turning at say half the RPM's that the outside tire is, the fluid coupling starts to lock and transfer torque to the outside wheel, which has more grip capacity
Let's you trailbrake deeper into the corner, for overtaking advantage and a faster lap.
Though admittedly the difference such a thing would make would be pretty small.
It will also lead to some corner entry understeer, but that can be tweaked. The concept is to give you more braking potential while cornering, not really to stabilize the car. As I mentioned earlier, if you wanted to do that, all you'd have to do is give the rear diff more lock with engine braking. Doable with a plate-and-ramp rear diff.
Grip is a four letter word. All opinions are my own and not those of current or previous employers.