Ya'll right, I'm wrong. (for the young guys that need that sort of thing, I may even have some trophies here somewhere).
With all the talking over each other, pseudo science v. pixie dust arguments, we're missing the point. Length of stem does not change the steering characteristics of a bike, but it certainly appears to, because it magnifies or diminishes the lever, making an equal input (deliberate or inadvertent) have a different magnitude. And yes, one certainly counter steers when steering with one's butt, it;s a lean and pivot of the hips.