Not so. It would depend on the enclosed volume of the vessel, the number of humans and animals aboard, and the period of time during which the upper hole is kept stoppered.
So now you are trying to convince us that in addition to all the other mythology surrounding the Jaredite barges, they also had airlocks. Didn't anyone ever tell you that when you find yourself in a hole, the first thing to do is to stop digging LOL.
I said nothing about airlocks.
Run the numbers. lack of O2 is only one component of the equation, CO2 buildup caused even more problems. O2 concentrations of 19.5% at sea level are IDLH conditions for workers, and it doesn't take much for a air-tight chamber with people and animals to deplete 2% of the oxygen (normal O2 about 22% at sea level
I said nothing about airlocks.
They are of necessity for a moon pool to function within a boat - do your research better.