Are you conveying the whole story? Is the approach you mention being advocated as a long-term method, or as a remedial technique - maybe for gross overcontrol? I've not heard of the exact situation you describe but I know that some students are their own worst enemies in inducing instability.
As a very low time PPL transitioning to a very high performance aircraft, I recall a few exercises designed to get me out of the habit of inducing roll oscillations on final. I can't help wondering if your instructor is trying to do something similar.