The RVP of denatured ethanol is 3psi , but the RVP of ethanol above a gasohol mix is 18( vapor pressure varies per Henry's Law). The reference below says 17 but I've seen 18 psi in other places. So for purposes of what I am talking about the RVP of ethanol to be added to gasoline mix is 18psi(17psi) and I standby it.

The RVP of gasoline product prior to blending can very greatly depending on where it comes from in the refinery--allkylate or reformate gasoline has a different RVP than FCC cracked gasoline and the amount of these 'gasolines' depends on the kind of oil supplied to the refinery. Reformate or FCC gasoline typically has RVPs of less than 5, so blending in butane, ether or ethanol is necessary.
The reason you can't reduce the RVP below 5 psi is that you'd have starting problems from low rates of fuel evaporation.

http://www.ethanolrfa.org/objects/pdf/newRFA%20Fuel%20Ethanol%20960501.pdf

R^2,
I don't understand your comment about polarity. MTBE ether is also polar. Do you recommend putting lead into gasoline?
At any rate Feinstein wanted to waive the whole oxygenate requirement. Oxygenates improve performance and reduce the production of carbon monoxide, isn't this important?

As far as the 10% allowance for ethanol goes, the EIA example assumes 9psi RVP gasoline prior to blending. I suppose a refinery could make one pre-blend for ethanol and a different RVP for straight gas to be used if the EPA requirements were too tight.