[john_b]

He put himself in this position, likely with the intent to lie.

Both intelligence committees submit questions to intelligence agencies in advance, who can then comment on these questions and make requests for change (such as moving some to the closed session). This is done in private, so moving a question to the closed session does not reveal any information to the public.

Even if for some reason this question blindsided him, he could have refused to confirm or deny it in an open session, as others have pointed out. But he wanted to put the PR fires out, and telling Congress and the public that they didn't collect bulk metadata indiscriminately served that end at the time, but later came back to bite him (and hopefully cost him his job, if not more).