They just had a short story on this on MSN, asking if this assault, with Bale more or less turning himself in, was a publicity stunt.
The reply from the reporter was, (and I agree) that it was not. This movie was so popular it didn't need something like this to get more publicity. I'm sure sometimes these things are planned, but honestly don't think it's the case here.
That being said, I am glad if it's "only" verbal assault. Not that it's a good thing, but, just the thought of physically attacking your own mother (not to mention sister) is kind of disturbing to me.
TIS