I would draw your attention to the bolded section below. I'm keeping this rule because most of the time this rule does apply, but as I said down there, it is up to our discretion at the time of the offense. If it is clear that the people who would be killed are to blame for their own deaths, the person in the airlock is not to blame.
Nope, people will rush, crouch under the door, and close the airlock door AS SOON AS THEY CAN and it gets people killed because they were 2 seconds too slow.
We make allowances if it is obvious the players who were killed were dicking around too far away, we just give warning or make sure they know it was only acceptable because the players killed were screwing around and it was their own fault.
The rule stays because people abuse those things, but again, we are lenient in those few situations where they DID have the right to close the airlock on people.
I've seen people close the first one on croc so fast, that the person who activated the bridge despite running STRAIGHT to the airlock after they activated the bridge got killed by the door closing, since someone got the combo ASAP and someone closed the switch ASAP and the person who activated the bridge had to avoid some zombies. That's bullshit that they did the objective for the team, and are killed by people rushing.
tl;dr: many rules are dependent on the specifics of the situation, and will be dealt with on a per-case basis. The rule does not mean every person who ever closes the airlock needs to be punished.