I think that's not it. Kiffin is at war with Al Davis and the Raiders lackey front office and not the media. The media loves this guy; he's a lightning rod of controversy, a spectacle, and a constant source of bizarre columns.
If Kiffin hated the media, I sincerely doubt that he'd offer up so many juicy clues and tantalizing nuggets as to what it is truly like to work for Uncle Al. I rather think he was smiling because he deftly turned the tables on Herrera, who presented himself and the front office as fools all the way around. Fools for trying to undermine the head coach, fools for taking it public, fools for grossly underestimating Kiffin, fools for not dealing with the situation professionally, and fools for boorish behavior and stupidity.
What's not to smile about?