There was a lot of body contact for the refs to choke on their whistles.  It is easier to block a shot if your not going to be called for the body foul.  Announcer Jeff Van Gundy commented that this would have been called a foul if it had occurred in the first 45 minutes of the game.  However, this took place in the last second of overtime of Game 6 of the NBA Finals.  I suppose we will never know whether Danny Green would have made the 3 foul shots to tie the game and send it into a second overtime.