The Sport RWD class is inappropriately named as it allows 4WD cars as well. I think it's a case of directly copying the rules from the NHRA, then realising it left GT-R, WRX etc. owners out in the cold and just tacking on the "4WD allowed" bit into the class.
Of course, I could be jumping to conclusions here, I tend to think that 4WD is more of a hindrance than a benefit under 10 second times, and as such could compete with 2WD cars.
If you want to argue about traction, check out Adrian's street car 60 foot time.