As stated above, there should be no trouble with putting the PDK into neutral. That's what neutral is for. However if I knew I'd be stopped for five minutes I'd use auto-stop/start or just turn off the engine. For sluggish rush hour driving that moves 20 ft, stops, moves 20 ft, stops, etc. every few seconds I'd avoid auto-stop/start.
Jim, on my second Porsche. The first was a 912 in a long time ago in a galaxy far, far away.