Yeah, sorry, I misunderstood what you were getting at - of course, you're right as long as you take the front hub axle out of the equation by using the brake to lock the front wheel. Then the long contact patch at the front gives you effectively two ground contacts, and because the wheel is turned they make a triangle with the rear contact patch. Once you get your centre of gravity over any point within that triangle, you can stand still forever without having to make further adjustments.
Yeah, sorry, I misunderstood what you were getting at - of course, you're right as long as you take the front hub axle out of the equation by using the brake to lock the front wheel. Then the long contact patch at the front gives you effectively two ground contacts, and because the wheel is turned they make a triangle with the rear contact patch. Once you get your centre of gravity over any point within that triangle, you can stand still forever without having to make further adjustments.