In a related story, absolutely no one is surprised.
Maybe Bynum had a personal situation that needed immediate attention. At this time, there's been no indication other than "he just didn't show up."
This was completely avoidable if he did just decide to skip out. Bynum simply had to come out and say "no comment" over and over again. The media would have complained, but he wouldn't have been fined. But as usual, Bynum seems to care only about avoiding doing anything he doesn't want to do. Like defending Russell Westbrook. Or scoring points. Or winning games. Or listening in huddles.