Theory is great, it's the practice that's the difficult part 😁
Your right that the wood should only catch fire if there is enough oxygen/air. I've not had an issue with my wood chunks catching fire in my proq. I do occasionally on my Weber kettle.
However, I've started burying my wood chunks at the bottom of the proq fuel basket, then pile the coals on top of them. Harry Soo uses that method and he knows a thing or two.
That way the positioning of the coals also reduce the oxygen around the chunks. I make sure the chunks are aligned with the vents as that tends to control the direction of the burn.