It's not horrible, if you're going Tai Chi, but it's a punch designed to give you a work out, not a punch designed to hurt anyone. "You're doing it wrong."
He takes her hand and rearranges her fingers. "If you punch someone like that you'll just break your thumb. You need to put it here, so it doesn't stick out over your fingers. You want to hit with your knuckles, not the tip of your thumb."
Right from the start Shi is critical. He never said he'd be an easy teacher. He's harsh, critical, and he hates everyone on the planet. It's not a rousing endorsement. What he is, is competent, and he knows what he's talking about.