I had to stop (though I may resume later) at "People who buy less meat don't really spend less money on food overall, they mainly just spend more money on other non-meat food" -- it made me go "are you fucking kidding me" and wonder whether he has ever been to a supermarket. See also this -- differences in retail prices aren't quite that extreme, but that's because governments subsidize meat production, so even though not all of the money comes out of meat eaters' pockets, it still comes out of somewhere.

EDIT: I finished reading it, and... if I didn't know who Hanson was and he had posted somewhere that allowed readers to comment, I would definitely conclude he was trolling. Along with things that others have already pointed out, “per land area, farms are more efficient at producing "higher" animals like pigs and cows” -- where the hell did he take that from? Pretty much everyone I've ever read about this topic agrees that growing food for N people on a mostly vegetarian diet requires way less land, energy, and water than growing food for N people on a largely meat-based diet, and there's a thermodynamic argument that makes that pretty much obvious.

(I do agree that “meat eaters kill animals” isn't a terribly good argument because if it wasn't for meat eaters those animals wouldn't have lived in the first place (but that doesn't apply to hunting and fishing); but that's nowhere near one of the main reasons why I limit my consumption of meat.)