Social media lives and dies on engagement. You serve your audiences such provocative content — news, political hot takes, baby pictures — that they keep their eyes on you as long as possible.

When Facebook’s chief, Mark Zuckerberg, showed up in Congress on Tuesday and Wednesday, he seemed to be aiming for disengagement. Facing a grilling over data breaches and Facebook’s role in foreign interference in the 2016 election, he was interested in keeping the provocation, and thus the attention, to a minimum.

If the byword of platforms like Facebook is “stickiness,” Mr. Zuckerberg’s prepared, bland affect achieved the opposite. He was so unsticky, the questions slid right off him.

Washington had been prepared for a showdown since the revelations that tens of millions of users had their data “scraped” by the political consulting firm Cambridge Analytica. The major broadcast and cable news networks carried the hearing live. Mr. Zuckerberg took his seat Tuesday facing a sea of snapping cameras, a handy if heavy-handed metaphor for the invasion of privacy.