IMO, his article is dramatically better than his last line. He is quite accurately attacking Big Ag (something even a majority of farm groups do), but throwing all the subidies together and adding it to the burger is simply mathematically inaccurate. I don't think he intended that line to be taken literally (as in, we'd suddenly see meat prices skyrocket that high), but it leads to a pretty unjustifiable soundbyte nonetheless.
I get meat untouched by subisidies all the time, and it sells for very nearly the same price as subsidized meat. Unfortunately, most of the subsidies are really just giving some companies a monopoly, which they abuse to control prices. The majority of feed (for example) is owned by a couple multinational countries because of the subsidies we're discussing. Those subsidies are actually an obstacle for small farmers, who very arguably could resell their meat for the same (or less) than Grocery Store prices if their costs weren't artificially higher than they should be.
Unfortunately, this is where it gets complicated, the subsidies now amount to 44% of plant farmer income. It will devastate the plant farmer industry to strip away the meat subsidies too quickly or carelessly.
I mean, here's something you might not realize about the subsidies. A good deal of the money from them come from farmers. Have you ever heard of the Beef Checkoff Program? It's a fee paid by farmers, ranchers, and producers every time they sell commodities... like beef. That money used to be voluntary and used for meat and dairy marketing. Now, it's mandatory and used to subsidize feed to Big Ag. In a microcosmic level, it's impossible to say subsidies will increase the price of meat when it costs the rancher money on the net.
The farm subsidies (all of them, not just the meat subsidies) really need to be cleaned up. They're not about helping an industry, but about lobbiests having locked in competitive advantages at the expense of everyone else. ( ref )