Most memorably, Brett Kavanaugh may have salvaged his Supreme Court nomination on national TV in a Senate hearing in which he showed Mr. Trump his own furious reflection. After Mr. Kavanaugh was accused of sexual assault by Christine Blasey Ford, Mr. Trump was disappointed by a restrained interview on Fox News in which he believed that Mr. Kavanaugh had come across as feeble. After Mr. Kavanaugh came back and detonated in front of the Judiciary Committee, Mr. Trump tweeted a delighted review, and stuck with him through confirmation.

In Mr. Acosta’s case, the charges against Mr. Epstein are so ghastly, and the stories continuing to emerge from his accusers so numerous and wrenching, that aggressive defensiveness and counterattack were not likely options.

But neither was apology, given that for his boss, the presidency means never having to say you’re sorry. (This was underscored in Tim Alberta’s recent reporting on the Trump campaign’s reaction to the “Access Hollywood” tape; the candidate ruled out an ABC interview that, he believed, would be about “extracting as many apologies as possible.”)

So in his TV defense, Mr. Acosta was caught between the indefensible and the unapologetic. He couldn’t say he was sorry, and he couldn’t seem not sorry. He instead seemed to want to muffle the controversy in a blanket of vague sympathy and lukewarm language, sidestepping the specific questions of why his office had not prosecuted the case more aggressively.

As for his present case: “I’m not here to send any signal to the president,” Mr. Acosta said. And yet, asked whether he had any confidence that the president would keep him on, he segued from “I serve at the pleasure of the president” to serving some of the talking points that most pleasure that president, praising the administration for “creating growth” and for standing for “the forgotten man and woman.”