"....and ABS assistance is required. " - I guess that is the caveat there. The point of track driving is getting round as fast & efficiently as possible. With PSM off and limiting your slip angle and ABS assistance the computer will allow you to explore limits not possible/prudent on the street. PSM allows a certain slip angle (5-7 degrees)before cutting with the nannies.
At the AutoX, I think that for everything up to and including threshold braking, the PSM will stay off if switched off. If you get into your ABS you have probably over cooked your transition and the car knows it. The cars also have a yaw censor, accelerometer etc which combined with other inputs help keep you from balling the thing up.
Good article here:
http://www.deter.com/porsche/PSM.html
Explains it better than I ever could.