Sorry, I misunderstood. (I didn't watch because we don't get NBC in HD in my state.)

But rule 24 doesn't require him to take complete relief from the obstruction. He merely needs to drop the ball at a spot that avoids interference from it.

And I didn't see the drop, but in the photographs you can see a pretty sharp curb on the cart path. If the curb had been interfering with his swing he certainly was entitled to relief from it, and he could have dropped the ball on the cart path at a spot that avoided the interference.

And I note he used a hybrid, which would be pretty easy to hit from a cart path.