In this matter, he's an idiot and just making **** up (his claims of "we're seeing hundreds of thousands of people losing 30, 80, 150 pounds.." and implying this is not only happening but is strictly due to removing wheat from the diet---gahhh). That doesn't mean knowing your individual metabolism well, not OVER-eating anything, ingesting less processed grains (or other foods) and eating a variety of grains (good ones mentioned already) aren't all typically healthy practices. They are.
I endorse skepticism, but I'd amend it to "Stories like this are why I always take Stories like this with a bucket of salt." When you have such an out-of-the-norm contention such as this, the burden of proof is great. Getting attention for your extreme and provocative claims is not only easy in today's media, it definitely helps book sales (like the agnostic neurosurgeon promoting a story that he saw mystical God stuff while in a coma, and became a believer, just in time to push book sales).Stories like this are why I always take health food advice with a grain of salt. (see what I did there?)