I really like Logan, but the third act with the kids using their powers feels a bit...traditional, which is not a bad thing, but considering most of the film was somewhat grounded, considering it has mutants with powers, the ending was too big. Once the kids started using their powers, it became more X Men 3 than NCFOM, imo. Also, those kids were pretty powerful, so I don't get why they were so scared of some humans with guns. One of the girls alone mad a guy explode and the leader of the kids lifted a whole truck with his...mind I guess? It was a bit much, imo. If they had more grounded abilities like X23, I could see why they wouldn't fight
They ran because if they got shot they'd be dead. Sure maybe they'd take out some of the Mercs but they'd really be taking a chance with their lives. X23 has her healing ability but the other kids didn't.