The argument is bogus: either way they should be installing doors in each station preventing track access. This is basic safety: keep people off the tracks so they can't be hit by a train. This is also air quality: keep brake dust out of the air in the station.
Maybe you decide automation isn't worth it, but you still want the doors, even if it means hiring someone to open them.
The above was also stated by one of the comments, but it is worth bringing up.