The needs of the many outweigh the needs of the one, the person is ejected, if they are fortunate on the side that still has air and you can force your way through an atmosphere containment field, it's only meant to stop air, shuttles etc. can pass through them all the time, but it would hurt like hell. Security fields are a little different and a lot more intense. The point of it is to save as many people as possible, it wouldn't make sense for it to have a failsafe that delays that if some fool is in the way and what a perfect tool it would be for a suicidal madman to kill people than just stand in the path to prevent a force barrier deploying in an emergency.
There's some historical precedent for someone to have a very bad day if they are obstructing a safety field as it deploys. A good while ago now, but I was reliably informed by the Chief Engineer of a UK flagged merchant ship which was maintained to Lloyds 100A1, that a human body or body part would not cause any significant issues for the integrity of his watertight bulkhead doors if they were obstructed while closing. The doors would, however, cause significant issues for the integrity of the body. In an emergency, the doors closed under massive hydraulic force, designed to shear/slice through anything other than something like a heavy structural beam.
What I really popped in to say, however, is that the "A Good Start" mission given by Hosa is still bugged and seems impossible to complete, as there's nowhere to pick up the shield generators that he is supposed to give to you. It's also impossible to discard the mission once accepted, as the button is greyed out.