Jerry,
Probably because the bunker was not "closely mown".
Rules of golf allow relief from embedded ball through the green on closely mown areas only. (Some courses have a local rule that allow relief "through the green".)
25-2. Embedded Ball
A ball embedded in its own pitch-mark in the ground in any closely mown area through the green may be lifted, cleaned and dropped, without penalty, as near as possible to the spot where it lay but not nearer the hole. The ball when dropped must first strike a part of the course through the green. "Closely mown area" means any area of the course, including paths through the rough, cut to fairway height or less.
EDIT: But just read that normally the PGA tour has a local rule 'through the green' so I am not sure now. Maybe they didnt this week due to the waste areas?