Yep, that is why the plot of Infinite was to me more a bunch of not fully thought through but cool sounding concepts instead of a proper and fully consistent story and world. I like the game for its art style, game play and atmosphere, but it is 100 % not making sense.
And now that you spell it out to me, I never realized before how directly contradicting that ending was to the whole concept of Bioshock 1.
Because to me it lost the point at the moment where they said:
spoiler
There are infinite Raptures. Because then we only saved them in that one single world and there are unnumbered other worlds where saving them didnt happen. So why even care at that point or feel great for saving 1 out of an infinity?
The muzzle isnt for the kids benefit, its for the rest of us!