First off, I have not read through all of that article, but I will answer how zoom lenses with variable apertures work if that is what you are asking:
The camera knows because the lens tells the camera what aperture it is. In reality, the aperture does not jump half stops or whatever when you zoom with these lenses as it reports - every mm you change the FL, the f number also changes slightly, because it is defined as the ratio of the focal length and the opening. On these lenses with variable max apertures, the opening does not change, but the aperture is reported in discrete f-stops for practical purposes.
See here:
F-number - Wikipedia, the free encyclopedia
This doesn't really change metering because f-stops are relative and light is always variable anyway - it may have an effect on manual flashes or auto thyristor flashes though, but I'm sure there are always small differences in f-stops between lenses anyway.