I have a feeling he did this so that people on internet forums would say "Christian Bale flat out rules".
If he was sincere, he wouldn't have made a public media event out of it. He did the same thing with that reporter prisoner because it was relevant to a movie he was promoting. If he wasn't promoting that film, he would never have done that. Same here. He has been on an image reinvention campaign since that Terminator Salvation fiasco.