I think he did his job. He passed a hearing in front of the congress, while telling as little as he could.
What he did, of course, for HN / tech people / journalists was fiasco, because we know what actually happens there. For the average people it was another reassurance, because now they say "Facebook is okay, the guy went in congress and no consequences followed, so it's good."
I tend to believe that the questions and the hearing itself was so bad and uneventful, because Facebook probably holds tons of data and collaborates closely with US government. So it will be quite unfortunate for the government and for Facebook if the real questions are being asked.
I really enjoyed reading the commend of @DyslexicAtheist [1] from yesterday's thread.
> it was a sham because asking hard questions would require them to admit FB being an important asset for US own intelligence operations.
1 : https://news.ycombinator.com/item?id=16811281