[Bobnova]

LN2 does not oxidize.

LN2 becomes N2, this adds to the amount of N2 in the room and displaces the other gasses. It forces out some N2, some O2, some co2, and some of every other gas.
The percentage of the room air that is N2 goes up, and the others go down.
Hence, if you don't get more oxygen into the room you will eventually have a room with 99.9% ln2 and .1 or less% oxygen, and rather dead inhabitants.

Oxidizing means combining with oxygen, which N2 does not do at normal pressures and temps.