He's going to try to say that it was his "character" and not him. Because in his mind it absolves him of the responsibility for his actions. He's going to make the claim that he's such a good actor that when he's on set, he becomes the character and ceases to be himself.

This is my really stupid take on what he's saying... But this guy is such a narcissist that I wouldn't be surprised if it turned out to be the case.