Oh that's easy to solve: simply insert a gene that makes biofuel corn toxic to humans, rendering them non-edible and solving the fictitious moral dilemma.
I think you were joking, but the sad part is, yes, that is what they do (minus the genetics) in order to avoid import restrictions (that apply to food but not "denatured", inedible corn/biofuel).
And it's long been practice to make alcoholic substances toxic if they're not intended for human consumption so that they avoid regulations and taxes that apply to alcoholic beverages.
