Bale takes acting pretty seriously, as seen in The Machinist:
Apparently he is taking his roll in the new Terminator movie pretty seriously too: before shooting he set up a meeting to talk with the director to talk about how to bring an emotional connection to the film.
That said he is still an actor. I don't think his job is demanding enough to warrant that type of yelling. Perhaps he should have turned that anger towards the paparazzi?
What made Bale's rant a dick move was that it went on for 5 minutes. It was clearly a projection of anger. Almost verbal abuse...I don't understand how people can get that angry. I've worked 2 large-scale office jobs, and no one likes the angry people.
I think it was unprofessional. I understnd the lighting guy made a jackass mistake. I understand that Bale takes acting seriously. But come on! Everyone makes mistakes.