And all gas molecules radiate...an O2 or N2 molecule can radiate energy that they acquired via collision with another molecule when the molecules become so rarified that energy movement via conduction is no longer possible.
You are starting to sound like BillyBoob.
What wavelengths are O2 and N2 radiating away energy? Why does radiation start at cold temperatures high up? What could possibly stop it lower down?
An aside to illustrate the concept...
CO2 has three vibrational states but only the 15 micron band is important to atmospheric physics. Why? Because common atmospheric temperatures are too cold to produce the other two vibration states. CO2 would happily accept the higher energy photons but they would have to come from a high temperature source.