I believe this concern is addressed by the next post in the series. The current examples implicitly only consider two possible outcomes: “No effect” and “You do blah blah blah and this saves precisely X lives...” The next post expands the model to include arbitrarily many possible outcomes of each action under consideration, and after doing so ends up reasoning in much the way you describe to defuse the initial worry.
I believe this concern is addressed by the next post in the series. The current examples implicitly only consider two possible outcomes: “No effect” and “You do blah blah blah and this saves precisely X lives...” The next post expands the model to include arbitrarily many possible outcomes of each action under consideration, and after doing so ends up reasoning in much the way you describe to defuse the initial worry.