That indeed is another way to control mixture over the entire throttle range, that WILL work. It is not as compact as the solenoid, but it IS a surefire way, and it absolutely should be easy to make with simple tools and equipment.

What I am wondering is how sensitive the secundary air intake (the airbleed) will be to dust collection, and how stable it will be over the range of ambient conditions.

That is no criticism, just genuinely wondering becvause I have never overhtought THIS particular approach of instead of modulating the fuel, modulating the bleed-airflow.

I absolutely like the idea for its simplicity and for its "being understandable".

I doubt however, if a temperature and atmospheric compensation like we had on the solenoid would be easily achievable, because it is harder to quantify things..