What makes switchgrass a reasonable alternative? Cellulose ethanol costs a lot more than corn ethanol, and so the subsidies would have to be a lot more. And what exactly do you think the corn farmers would do if switchgrass subsidies made it worth more than corn production? Yeah they'd switch to switchgrass and the food shortages in poor countries would continue if not worsen.

Perhaps one day the Left will see the wisdom in letting the free market work, but not, probably, in any of our lifetimes.