You're doing exactly what you claim they're doing -- misrepresenting the article. They're saying there's possibly a virus that can cause obesity, and it might come from chickens. They're not claiming that it causes all obesity, just that it may be a vector.
The article shares a boatload of interesting, relevant evidence of a correlation between certain viruses and fat.
Plus, the article actually expresses some doubt that the "hook" was the cause (it was not a hook, it was a rooster's talon)