Well, Dr. Huizenga's motivations to critisize WLS may lie in his investment and celebrity on Biggest Loser. Biggest Loser is a brand, and right now it's a lucrative brand to be associated with and Dr. Huizenga is profiting from it, even to the extent of opening his own resort style fat ranch, which I'm certain is aimed at a particular wealthy demographic. His views are very single dimensional and ignores the many complexities of mental and physical reasons for weight loss. He has been quoted as citing a study comprised of just 35 subjects, hardly a statistically accurate sampling, for many of his conclusions. Although we might expect him, as an MD, to proffesionally consider other medically accepted options, he chooses to select publications that support his business. I believe Dr Oz has been critisized for questionable claims, seems to be a Hollywood weakness.
In the end, Dr Huizenga can make all the claims he likes, it's a free country, but results speak louder than words. In actuality, he has not found the "magic pill", I therefore suspect his program, or Biggest Loser, is not likely to produce results unlike many studies with thousands of data points, which say diet and exercise has a low statistical success rate vs. WLS. As far as the damage he might do to discourage obese viewers of the show from WLS, I don't think he has the credibility as a TV personality verses a patient having a serious conversation wth their primary doctor or their surgeon.