Well, the OP claimed you yelled, "stand up", he claimed to have been focused on skiing on the arches of his feet, he says he did some one ski turns, he claims by being in these new positions that he finds it easy to turn his skis and has no quad burn.
Some of us suggested these things early on, would an Instructor training for full cert suggest that a static position is ideal in skiing?
This Instructor never made such statements but has been guilty of yelling, "stand up" to many of his clients as you did with the OP.
P.S. I was giving you a compliment my friend.: