Wow.
I saw this on some other forums I frequent and... well, I just had to laugh.
I'll admit, the lights techie shouldn't have been pissing around with the lighting during a shoot - if there's a problem you should at the least wait until a shoot's been finished, THEN raise the issue. Running on set and twiddling them around during a shoot obviously can distract the actors and cause problems and on that hand, I have to give it to Bale: he's at least justified in his thoughts.
That being said: the dude's supposed to be a professional. There is absolutely no way I would ever have allowed anybody under my employ to fire off like that, no matter what the problem - there's always a solution and a way around things that doesn't involve threatening or shouting. Bale should have been taken to one side, allowed to calm down, and then the issue should have been raised calmly and resolved peacefully.
As it is, both of the parties involved acted extremely unprofessionally. The lights guy should have known better, and Bale definitely shouldn't have gone off as he did - hell, neither party should have been ALLOWED to go through that whole thing.
My $0.02 on the matter.