Also not an engineer, but I would have thought there was considerable side to side pressure being put on the spindle. Now matter how pure your pedal stroke is, a vast majority of the force is being applied down. So, when you pedal down on the left, wouldn't the spindle be pushed down on the left?
An inch is not much, but if you consider that the total distance from the outer of the BB shell to the ball of your foot is maybe 4 inches, then that would seem to add 25% more leverage. Is this wrong?
jim