It does sound like it's probably an exclusion, but I would be curious to know the context. My insurance is worded similarly in the it says that it says surgery to primarily treat morbid obesity is not payable. At first, it sounds like they won't cover it, but it goes on to say it is payable in the presence of morbid obesity and particular co-morbidities which will benefit from surgery treatment. Can you copy and paste more of that section, possibly?
Disclaimer: I don't work in insurance, but I was employed as a worker's compensation medical biller, and specialized in appeals.