Not to excuse a crazy movie star's ugly rants, but I wouldn't be surprised at all if there is a double standard at work here...
I’m not sure if Alec Baldwin has been in any big movies since his telephone rant to his daughter, but I do know that few here on FR defended Alec Baldwin for that incident.
However, there are plenty of people here that will defend Gibson for his Anti-Semitic, violent and racist rants.