he doesn't know anything about wood gas.
It's primarily hydrogen, carbon monoxide, and methane as the energy components. Carbon monoxide is a slow burner and often ends up in the generator's exhaust.
The greatest single component is worthless: nitrogen. This typically represents about 50% of the gas emitted.
I have looked into nitrogen scrubbers and they do exist, but not convenient for small-scale operations. Further, the system I fiddled with incorporated 02 sensors (from a car exhaust, easily obtained) in order to monitor the fire's efficiency to regulate air intake and to monitor the output of the exhaust from the generator for other adjustments. Pain in the rear, plain and simple. Not trivial.
I used an Arduino to monitor both of these 02 levels as well as temperatures at various stages. The most effective scrubber was using vegetable oil as the filter. Done right, they're complex, bulky, and finicky. You really should own a tree farm to use this method. As in, cut and plant in rotations. It takes a bit of wood and it goes fast.
I dropped it after a lot of time (~1 year) spent on trying to get it to be reliable/practical. The myriad YouTube videos make it seem easy and simple. It isn't if you plan on keeping your generator for longer than a few months and run it more than occasionally.
Given the complexity of the internal combustion engine -- and the parts which should be kept on hand -- I went with steam instead. I bought an engine and built a boiler. I could make another engine in my shop (no spark plugs, wires, electronics, exotic metals, fancy engineering/tolerances, or parts which may be hard to obtain in SHTF scenarios). Ditto for the boiler.