As has become the case with most controversies, we have made it a choice between two extremes. Some say Serena did absolutely nothing wrong and is a hero for standing up to the chair umpire and calling him a thief.
The other side says takes joy in pointing out that the umpire acted within the rules and say that Serena deserved the consequences. There was absolutely nothing dubious about the chair's decision.
Clearly, the truth is in the middle of these extremes. Each warning against Serena was technically legitimate, and she should not have called the umpire a thief. On the other hand, it would have been best if the umpire had used a little discretion and not issued a game penalty. Thief is not such a vulgar term that he couldn't have chosen to withhold the penalty.
Serena was not blameless or heroic for yelling at the umpire, but that doesn't mean he made the best possible decision, either.