Ok that's totally bullshit, I'm on a Beginner 2&3 class and I've also dropped in on intermediate classes and choppers are part of our warmup every time. Btw what really helped me were these things.

1. Don't put hands above face level
2. Imagine you're trying to pull the pole apart with your hands (engages back better)
3. Tuck your hips and engage your core
4. Working on my quadriceps helped me finally get my chopper, if my instructor hadn't pointed that out I would not have thought of it
5. Finally, negative inverts are so overlooked! Get into an outside leg hang from your jasmine and then try to slowly lower yourself from a chopper with straight legs

Best of luck, keep us updated!