I've wondered this for a long time too. It's named after the Hindu Kush mountains where the race was found but I've noticed so far, anything with Kush in it's name is usually VERY pinetree tasting.
Again, KUSH simply means that the plant or the plants parents or even grandparents originated in the Hindu Kush Mountain region. Thats it. Nothing more, nothing less. The part about the pine taste might just be the dominant and sought after trait of kush breeders.