suspension droop. If he gets the GCs he will have that same issue, which he mentioned numerous times. GCs have a shorter spring but use a stock/full-size shock, so they will be free to move around when the car is off the ground.
My GCs have a good inch at least between the spring top and the perch when the car is lifted. That's just a product of how thy are designed. NOTHING like his reasoning for cutting coils though.