I'm pretty sure you're right sal.... it wouldn't make sense to activate the brakes once the differentials are locked because that would thereby hinder both tires from rotating.

Also, on Sunday I pulled my friends 6500# 28' boat out of the water using a half beach/half paved ramp and had all 4 of my tires spinning in 4 low.... at no time did I hear my ABS pump kick in to activate the brakes, and I didn't even press the button to turn off traction control.