The “probability” of the imagined world is low, so the opportunity cost of this action makes it wrong. If there was a world fitting your description that had significant “probability” (for example, if you deduced that a past random event turning out differently would likely lead to the situation as you describe it), it would be a plausibly correct action to take.
(The unclear point is what contributes to a world’s “probability”; presumably, arbitrary stipulations drive it down, so most thought experiments are morally irrelevant.)
The “probability” of the imagined world is low, so the opportunity cost of this action makes it wrong. If there was a world fitting your description that had significant “probability” (for example, if you deduced that a past random event turning out differently would likely lead to the situation as you describe it), it would be a plausibly correct action to take.
(The unclear point is what contributes to a world’s “probability”; presumably, arbitrary stipulations drive it down, so most thought experiments are morally irrelevant.)