But in real life, objects, including light emitters, are pretty complex. I can even construct a spinning object with "black and white" stripes that appears green, even in monochromatic light.
And, of course, green pigments are usually mixtures of non-green pigments.
Green is a construct of the eye and brain. The Benham Top demonstrates that color is encoded by the retina as a firing rate for neurons. When you induce the firing rate with a non-chromatic pulsating light source, you get the subjective sense of color. I've done this under carefully controlled laboratory conditions, using a monochromatic light source.
I'm not sure I buy that. Your eye and brain may be fooled into perceiving "green" in some instances, but that sounds more like an instance of "aliasing," which is a well-known phenomenon in signal processing.
We could test your statement, and the control would be to see whether people with "normal" vision (however defined) would ever identify your "Platonic Green" as some other color. Dollars to donuts they won't.
Since we're talking about colors:
How does the poison arrow frog communicate to animals that are color blind that it is indeed poisonness?
We know animals avoid brightly colored animals as food in the wild, but not all animals can see color. If it is indeed only a matter of the brain, how come these other brains can preserve their own lives?