no actual penetration so jack is still untouched.
There is penetration, just not balls deep.
Comparing to the knuckle, and assuming the knuckle is an average sized one and is roughly about 1 inch.
This means the dick has a diameter of ~2 inches at the shaft, and a glans has a diameter of ~3 inches at widest point.
Roughly 1 inch of the glans is inside jack, to accommodate this penetration Jacks anal circumference has been dilated to roughly ~2.5 inches.
look carefully at the picture at full size, you can see the anus (creases and a different color from the rest of her skin) above and below the penis which make it quite clear that penetration is occurring as well as the scope of it.
Whether it counts for the purpose of NTR is not something I am going to bother debating.
Several people indicated they think it does not count (yourself included).
Several people indicated they think it does count (myself included).
Everyone can decide for themselves if it counts or not after seeing the picture