It's worth hearing the whole story on these sorts of things. One of the Assistant Directors (and also executive producer, but his role as an AD is more relevant here) has said that Bale was normally completely professional on the shoot and simply lost it for a few moments at the end of a very long hard day, and after that was perfectly fine again.
Some of you are also misrepresenting the situation somewhat. The Director of Photography walked onto the set and into the shot during a take to make an adjustment to a light. From what Bale said, this was not the first time this had happened, and there was an issue with this DP constantly moving about during a take.
If a low-level crew member did something like that there's a good chance they'd be fired on the spot. It's an absolute no-no. You NEVER walk into shot during a take.
Bear in mind this happened during filming of one of the most drama-intensive scenes of the entire film. While some actors have this surreal ability to snap in and out of character, most actors have to go through a process of descending into their character, and for some it can be quite hard to do, and hard to maintain. We've all heard legendary stories of actors who were so "in the moment" that they did things in character that were not intended. Martin Sheen smashing the mirror in Apocalypse Now, and Juliette Lewis breaking Tom Sizemore's nose in Natural Born Killers.
I can imagine an actor being irate at a crew member for screwing up a dramatic scene - it takes hours to set up a shot and get everything exactly right, and even though you can do multiple takes, once you get that one performance/shot that nails it, you will never, ever get that same perfect shot again.
If that particular crew member has screwed up shots previously, and if that crew member is a HOD who should know better, and if the actor is tired and stressed by a hard day's work and perhaps the recent untimely death of a fellow actor, yeah, I can imagine the actor losing it and biting the guy's head off.
This sort of thing is actually pretty common. As as 2nd AD I once had to interrupt a very angry argument between a Producer and Director to tell the Director to get on set so we could start shooting. At final technical rehearsals for a stage production of Les Miserables me and the entire rest of the cast hastily made our way out of the auditorium when the director and stage manager started an outright screaming match with each other.
In those sorts of highly strung close-proximity situations, people lose it. True professionals are the ones that get over it quickly, move on, and keep working. We have no evidence that Bale held any sort of grudge against the DP - he even says in the rant he's a good guy.
Let's not judge too soon.
(By the way, the OP doesn't make it clear, but this incident happened months ago - the news is that audio of the incident has just emerged)