OkUnless you are a tier one operator, you are correct, the likelihood of being left on a mountain alone in enemy territory is almost nil. But remember this discussion was not about what the everyday guy would do or why they might want to select one firearm/round over another. The everyday guy needs all the rounds they can spray with minimum recoil as not to offend weak wrists and recoil shyness. so I agree, the 9mm would probably be a better choice for that guy. And that guy did actually have a Beretta 92 on that mountainside so that is what he though was best. But I can see why the other round would also work quite well despite any capacity issues. Which I personally think is an overrated requirement and sometimes can be a crutch, but that is for another discussion.
But ammunition choice does actually matter when you are looking at both rounds in the required configuration, and countless uses of the 45acp FMJ are there to show the terminal ballistics of that round.
The question should not actually be about the round because 45 ACP FMJ is better than 9mm FMJ....The question should actually be, why use a 1911 platform when there are platforms that allow you to double your capacity using the 45 ACP.