Here's the real kicker
I'm not saying that you should not do box squats with parallel shins. I am saying that box squats can also be done with regular raw squat form with the knees pushed forwards.
Yes, KK does his speed squats with regular box squat form; but he also does max effort box squats with his knees pushed forwards. You're doing a great job of making an ass out of yourself here so I suggest you look back at what I said (that box squats with regular raw squat form are fine for building a raw squat) and then watch the full KK video again and see what he does