Part of it is the image the PGA wants the public to see. I heard he flicked a cig onto the course and was caught on camera doing so. Also, many people who are advocates of the idea that golf is a sport, look down upon an overweight smoker. Compare him to an athletic, straight-edge, clean-cut Tiger Woods and it's clear who the media prefers to side with.

It is all part of the great demonization of smoking by society as a whole - nobody can pass up the opportunity to tut at a smoker and offer a negative opinion any more. Smoking used to be cool around the 80s and early 90s, nowadays frothing at the mouth at the evils of smoking is even cooler. There may be an element of the US media disliking the fact that their supreme athlete, Tiger Woods, was beaten by a fat guy who smoked on the course and so they are hammering into him for it out of bitterness, but I think that the general social trend to be anti-smoking is responsible for this coverage even more so.