The statement also makes sense if they are stock brakes and you will notice on the racetrack when you burn through them in a couple laps.
In that case you might notice the lack of sport brakes...
Full context in post #29. Elon was saying that AWD would neither have nor need the sport brake option. Implication being that a P on the track with 20" wheels and sticky tires would notice the sport brakes (so by golly they'd better be included)