if you try to keep a passive and quiet upper body while you steer or pivot your skis underneath it, your upper will follow the lower, staying square with the skis. Your upper is not attached to anything else to stabilize it otherwise. In order to give the appearance that its stabilized and independent from the legs, you have to use counter-acting muscle activations which gradually turns the upper out relative to the legs. You turn the legs in and the hip out at the same time. You push or pull muscles against each other.
You can pretend you are not or choose to ignore thinking about it, but those activations are necessary and you are using them when you create counter. Some people need to wake up their awareness of this in order to get better upper lower separation.
Also, some of the ski pivoting happens due to ski design, in other words, passively....and then even more counter-acting muscle use is needed to ski into counter.
BTS, that's exactly the point... when you do a pivot slip or javelin turn, instead of mechanically blocking your spin by saying "counter! counter!" and artificially adding tension, you work on getting the ski turning under your body. External focus instead of internal focus.