I thought that at the time, but then I remembered that Oscar Wilde line:Great effects, but if oxygen was so valuable why would a business simply vent out anything not needed?
The oxygen had no value at all... to the computer running the mining station, the computer that was busily trying to kill the only things that valued oxygen, the humans (humans who had, at the time of the Doctor's arrival, also ceased to have any value).A man who knows the price of everything and the value of nothing.
Of course, if one considers the whole scenario, it does begin to fall apart. For instance, why bother to send replacement humans if the existing ones are already there (and have to be killed to make room for the new arrivals)? That sounds really expensive. Why have any humans at all? Why not let the station computer control the suits (which seemed to be robots each with a human-shaped hole in the middle)?