From my TV memory of #1 Oakmont, it is an immenitly fair green because it's entire front is open. You (try to) land the ball 15 yards short and let it roll. Admittedly, it will take some bounces and pops, but the hole is playable, meaning, for me, that the golfer can readily complete the hole with a score obtained with in the Rules of Golf.
My previous Ballyhack threads and comments are made within the context that the severity of the hole may make completing the hole, with in the Rules of Golf, potentially problematic for some if not many.