Zubrin is the darling of the altspace community for doing exactly what he's trying to do here: allege that the forces that be are missing some obvious, easily solution, then skimming over all of the serious complications that led that "solution" to be unrealistic.

For example, when he talks about terraforming Mars, he pretends that there's enough CO2 to warm the planet and that you just need a little boost to get it started.  In reality, there's actually very little CO2 on Mars, even in the ice caps (about a meter on the north, about 8 meters on the south), and all simulations show that you need to pump ridiculous amounts of super-greenhouse gasses to warm the planet.  Zubrin then makes up ridiculous reasons for why launch costs -- something that people have been working on lowering for a century -- can just suddenly be slashed by a couple orders of magnitude.  Reasons which don't stand in the face of even the slightest bit of scrutiny.  Then he uses his preposterous launch costs to argue that hey, we can get lots of people there to colonize it!  And then he skims over the monstrous, centuries-long engineering challenges that would be needed to set up a self-sufficient chemical and manufacturing industry.  It's a house of cards that's missing its entire bottom layer.

Zubrin is doing the exact same thing here.  Food costs have only increased by 4%?  World food prices aren't up 4%; they're up 40%.  Not that Zubrin would care about being wrong by an order of magnitude.

It's simply ridiculous to think that you can convert a large chunk of the world's farmland -- which is what this would take -- into some other purpose and have food output remain the same.  That's completely beyond the bounds of any serious analysis of the situation.  Even crops grown on marginal lands still consume significant resources, and the amount of land that would need to be converted, especially with China and India's projected growth, is completely unreasonable.

And here comes yet another problem with the hype of ethanol: it makes for completely irresponsible decisions.  Let's just ignore corn ethanol, and the studies that show that even sugarcane ethanol is bad for global warming.  Let's look at everyone's favorite: cellulosic ethanol made from waste.  What do most of the new cellulosic processes do?  Well, they burn the biomass in a low-oxygen environment to produce syngas -- CO + H2.  They then use some elaborate and rather lossy biological or catalytic process to turn this to ethanol.  Well, gee, that's funny, because syngas has been used for most of a century to produce gasoline.  In a not-very-lossy, relatively simple, direct-catalytic manner.  This is how coal liquefaction, which powered Nazi Germany in WWII and South Africa in the apartheid era works.

So, why aren't they just turning it into "cellulosic gasoline"?  Because gasoline has a bad connotation, isn't a buzzword, and doesn't get tax breaks.  So they use an inferior solution -- one that requires car conversions, has lower energy density can't be shipped in normal pipelines, and so on -- over a better solution -- for a ridiculous reason.

Biofuels are not the answer.  The answer is cleaning up our electricity grid (which is an easier problem) and switching over as many transportation miles as possible to electricity (PHEVs and EVs), which is becoming increasingly easy thanks to rapidly advancing battery tech.