Well, in essence, tightening the AFM just makes the ECU think that there is not as much air entering the engine, and therefore injects less fuel. Of course, it also has further advanced timing maps for this because it thinks there is less air in there. Can be dangerous.
I don't think, however, that the AFM could be used to control bigger injectors to any reasonable degree. IMHO I just doubt that it would be adjustable enough, not to mention it would be pretty difficult to get this tuned reasonably well at any/all levels of airflow.
You could try it, but I just dont think you'd have a lot of luck. :shrug:
Another thing is that maxing out the AFM is quite easy to do, and would take a large adjustment in order to actually reduce the AFM value at WOT. Which might result in detonation/poor running at lower rpms/load points.