Hillary Clinton may not be indicted on criminal charges over her handling of classified email, but the F.B.I. director, James B. Comey, all but indicted her judgment and competence on Tuesday — two vital pillars of her presidential candidacy — and in the kind of terms that would be politically devastating in a normal election year.

The silver lining for Mrs. Clinton is that this is not a normal election year.

Mrs. Clinton’s campaign is built on the premise that she has the national security experience and well-honed instincts to keep Americans safe in the age of terrorism, and that Donald J. Trump does not. Nearly every day, she seeks to present herself as a more thoughtful and responsible leader.

She has spent months describing Mr. Trump as “reckless,” “unprepared” and “temperamentally unfit” to be president, and she has pointed to her four years as secretary of state and eight in the Senate as unparalleled preparation for becoming commander in chief.