To refer or not to refer - to third umpire

It happened again - in first test of AU-SA series here.

CricInfo commentry said ( 3rd over of SA first innings):
McGrath to Smith, one run, short delivery on the leg stump. Smith tucks it away behind square, Hodge picks and throws at the stumps, third umpire called for. Villiers is well in but he jumps off beacuse the ball was in line with him but he cant be given out since he is taking an evasive action there.

What do you think? Inzamam recently had a ruling going against him in similiar situation - here.