OK, so he leaves the girls because they are dead weight, But his sister was in the same situation. the only reason he knows the 2 girls he is with are good is because he knows them in the future, who is to say that the same cant be true for these girls. I mean, they would have escaped without his help.
Remember MC in the original timeline was beaten up and barely survived the first state of the apocalypse, but met up with his sister anyways.
It's almost like those comics have a master script that they have to follow and the character script said, time for MC to call people useless.