I agree with those folks who question the original decision to play those areas as HAZARDS. I don't think it's so much a question of whether they were "bunkers." It was a matter of deciding to make those sand areas (typically waste areas) play as hazards for the tournament. And that may have been a bad decision.
There is an analogy here: lots of courses have local rules to play grassy areas as water hazards, and if you find your ball in that area you cannot ground your club - even though there is no water to be found, anywhere around. So they aren't really water hazards but they have been designated as such by local rules. Now, water hazards are easier because they have red stakes/lines, of course.
But the rule was the rule and would have applied to Tiger or anyone else.
On the pga.com stream they read out the memo that was sent to the players and it was unbelievably clear and explicit: it said that all sand areas were to be played as hazards. It went on: they are still hazards even if they haven't been raked; even if they have been walked in by spectators or driven through by carts; even if they are well outside the ropes. This memo was placed inside the locker of every player, including DJ.