This is because we are vulnerable, more than folks apparently understand.
If we withdrew ethanol from Gasoline mixes now, the price of Gasoline would rise perhaps significantly. Not because, we would have less fuel, though this would probably tighten the fuel market considerably.. but as we will have given up our escape plan, the futures market would push the price of a barrel to $150 or more with no possibility of relief.
One of the distortions that is being used is that it takes more fuel to create a gallon of ethanol than a gallon of ethanol, and this is probably true.. but its not like you think. Not a gallon of gasoline, but equivalent energy such as Natural Gas, and fuel in creating the various components such as the yeasts and processing the waste materials. Such that we gain more than 1 gallon per gallon of ethanol produced. But, the problem of mass producing enzymes and yeasts for truly large scale production from non-grain sources is being worked out and this takes time and capital and testing at scale.
This has been laid out as a national security priority and not as as the most economical move in the short term but buying oil in a tight fuel market is not the most economical move.. but we will be glad if one day we find our supply cut by 25%.
Now many folks want to get us into a corner so badly that we have to start drilling and refining US Oil reserves, but that corner may not be something we get to turn. Its very much like deciding to elect a Democrat to show the rascally Republicans they need to shape up. Folks tried that in 2006 and see what we got, more Democrats and tax increases already passed to make the additional cost of fuel a joke compared to what they plan to take out of your pocket directly.
This is how conservatives are knee jerked into self-defeat.
Don't fall for it.
We can import ethanol from Brazil for far less than we produce it here. US ethanol production is payola to special interests, farmers and their politicians, nothing else.