The pedestrian in front of you has the choice to be steered or to ignore you--or more unexpected actions. Which ever they choose has nothing to do with the person behind them taking away their autonomy and everything to do with what they felt like doing with it at the time. Just because the wants of the person behind them and willingness & aweness and choice of the person in front align with those wants does not take away the forward person's self governance.
The point of that demonstration is that people do things without consciously thinking about them. You don’t have a choice, I am controlling your behavior in an extremely minor way.
My go-to example is being able to steer the pedestrian in front of you by making audible footsteps to either side of their center.