Definitely interesting, but I think that a fast-growing tree would probably create more O2 (consume more CO2) in its first 10 or so years. I think that big, old forests where large pieces of wood are dropping and rotting, etc, may tend to be on the neutral side of things.
I think that some studying of what type of trees to plant, etc is definitely in order. Certainly some drop less - and quite possibly they determine that the trees need cut down, turned to paper or paper products, and replanted every number of years.
When I think of the situation you are describing (CO2 neutral), I picture a dense, damp forest area. I feel like trees, properly spaced, may lean more toward co2 consumption.
Anyway, just a thought...
[1] https://biologicperformance.com/sealed-bottle-terrarium-gard...