Fortunately for Zack, he got zerg-a-fied. Red quarter domes form on a few locations on his skin as they take in Oxygen from the rapidly thinning atmosphere. Zerg growths...
They wouldn't save him from Zero pressure/atmosphere environments... He was still too human for that. As for everyone else...
Something people don't realize is that (in this situation) when someone says "You have 1 minute of air left" and you had three minutes to begin with, you have just about a third of the atmospheric DENSITY you had originally. It just isn't enough air to operate on at 100%.
One of the staff still alive tries to run for an airtight room. His lungs have been struggling to get O2 to his blood for the last minute and a half. His under oxidized mussels (coupled with the sudden drop in air pressure AKA altitude sickness) go 'lol nope' and he hits the ground. Discord walks past the man, still in the guise of the dead scientist. "Sorry man. Your only human. Unless someone asks me to close the airlocks you will be dead in a minute."
Everyone not in FULL environmental containment gear is suffering from O2 deprivation. Unless you are a machine like Discord.
You are having trouble breathing.