In French we call that technique "faire de la mayonnaise", as it reminds the way to make a mayonnaise with a fork.
I think that a good remedy is to send the pilot to a glider club. Have him look at the instructor's technique while spiraling in a thermal, hand him over the controls, and he'll see by himself that the mayonnaise technique won't make the glider climb. Hand flying is all about angle of attack perception, it's an extremely difficult skill to acquire, as it can't really be taught on the ground. Gliding is a very cheap way indeed to improve one's visual perception. Once your perception is accurate enough so that you can perceive not only a variation of AOA, but also the rate of variation, then you can anticipate accurately enough not to over control.
Light helicopter flying (R22 for instance) is also a good school for visual perception, but by far more expensive.