Donald Trump in Walterboro, S.C., on Feb. 17. (Luke Sharrett/Bloomberg)

There is a very good reason Republican presidential front-runner Donald Trump routinely disses Fox News contributor Charles Krauthammer. The veteran commentator, after all, exposes the emptiness of the suits worn by Bill O’Reilly, one of Trump’s chief defenders.

Tuesday night, for instance: On his eponymous show, O’Reilly introduced Trump’s “bizarre” and successful campaign to highlight a National Enquirer story alleging that, somehow, the father of rival Sen. Ted Cruz (Tex.) was linked in some grainy way to the JFK assassination. “His father was with Lee Harvey Oswald prior to Oswald being you know, shot. I mean, the whole thing is ridiculous. What is this right prior to his being shot and nobody even brings it up,” said Trump on Tuesday morning’s “Fox & Friends.”

With that stipulated, O’Reilly and Krauthammer launched into an exchange that resists abridgment:

O’REILLY: This stuff doesn’t do the Republican Party any good at all. I cede your point there but I know Trump. He is not — he gets emotional then he steps back and it’s a different guy. Go ahead.
KRAUTHAMMER: Do you believe he thinks that Cruz’s dad was associated with Lee Harvey Oswald?
O’REILLY: No. But I believe that he puts that out there just to create mayhem and creating mayhem has won the election for him. Has it not?
KRAUTHAMMER: Well, what you are saying is the end justifies the means.
O’REILLY: That’s what he says. He believes he has to win —
KRAUTHAMMER: You’re saying, Bill, you’re saying, I don’t care if he is creating mayhem, he won. I don’t think that’s the right answer.
O’REILLY: I’m not saying that. I am just telling you, how he — you say, okay, I don’t want him with the nuclear code. And I’m saying to you, a lot of this is theater because the odds of him winning the nomination when he began in June were a million to one and he won it by creating mayhem and it was a brilliant strategy. It worked for him.
KRAUTHAMMER: He wins it by floating conspiracy theories that you know and I know are in twilight zone land. In the same way that he led the birther movement. That wasn’t, you know, ancient history. That was five years ago. Do you believe that that was also a reasonable pursuit?
O’REILLY: No. It got him attention and it got him the goodwill of people who don’t like President Obama.
KRAUTHAMMER: Doesn’t that tell you something about the temperament?
O’REILLY: It tells me wants to win and his playbook is much different than the traditional playbook.

Essential context for that chat is O’Reilly’s status as a longtime, vanilla-milkshake-sharing friend of Donald Trump. No dummy, O’Reilly surely recognizes that Krauthammer schools him on this topic. Back in March, after some other Trump outrage, O’Reilly defended the candidate on similar terms, saying that he gets “emotional” and doesn’t always process his thoughts too well. O’Reilly’s suggestion then that Trump “readjust” his rhetoric triggered a repudiation from Krauthammer, who called it “weaselly.”

These pointed-but-highly-civil disagreements make for good television, as Krauthammer articulates as strong a case against Trump as cable news can provide. Accordingly, O’Reilly deserves plaudits for hazarding these pro-Trump arguments in Krauthammer’s presence. With Trump’s ascent as the presumptive GOP nominee, there should be more of these moments down the road.