Why the fuck would you send people forwards to fight a losing war. It never occurred to anyone in the movie to try and stop the war from happening. And when they do propose that idea as last ditch idea, they are told to fuck off!

Its even shown that the timelines are separate (and in my mind that means different univerers) so why the fuck would one universe agree to send it people to another universe which would have ZERO impact on the world they are leaving. The war is STILL going to happen on the world they are leaving!!!!!!!!

The only way to save the world, period, is to prevent the war from happening or gearing up 30 years early to win the war.