Yes! That clears the mystery of why he didn't see her . He was laser focused on leaving and didn't expect anyone else to be on that floor.
Poor DM!
He might have also had literal tunnel vision from an adrenaline rush. I've had several adrenaline rushes and the most intense one I literally lost my peripheral vision. I could only see my hands moving in front of me, like in a first-person shooter game. I was still "calm" in that I methodically took steps and actions to try to protect myself and other train passengers in a very horrifying situation, but all the edges of my vision were just blurred. Even in my memories of the event, it's quite bizarre. I had to Google it after and it's definitely a thing - BK could have been having a crazy adrenaline rush after what he did and not seen DM.
JMO