Unpopular view as it may be around here, most referees do get the majority of decisions right. If you count the number of decisions that Williams had to make in that game, the overwhelming majority of them wouldn't have raised any eyebrows whatsoever. If a ref is unlucky, he'll have one huge, contentious decision to make in a game which will cause controversy, Williams was "unlucky" at the weekend that he envountered several.
He'll have been assessed and, judging by the FFA Referees' boss comments, made aware of any shortcomings which might have been identified in his performance. Referees at that level are also expected to be very self-critical.
I'm not Ben William's Dad, and I'm not posting this to either attack or defend him, merely saying that refs do screw up and when they do they're usually the first to admit it (in my experience)
p.s. Agree with your comments bout Collina, LG, but ask Everton fans what they think of him! :-)