Brian Williams will not appear on the Late Show with David Letterman this Thursday, canceling a long-scheduled appearance in the wake of an investigation into his inflated claims about taking fire while in a helicopter in Iraq, an NBC News source confirms. Some industry navel gazers say he’s missed a great opportunity by canceling.

Lettermans Thursday broadcast was on track to do a big number, and get a lot of press coverage. Letterman hadbooked Williams as his guest that day a huge get for a ratings-sweep night.

No telling what Williams originally intended to plug in his appearance on the CBS late night show; the booking was made before Stars and Stripes published its report debunking Williams claim he was in a Chinook helicopter that took a rocket-propelled grenade in Iraq in 2003. The booking was canceled this afternoon, under cover of the weekend, when viewers tend to consume less news. Not coincidentally, NBC announced Friday it was launching an internal fact-gathering investigation of this andother Williams claims over the years, to assess the damage to its brand. On Saturday, Williams choseto announce he was taking himself off of Nightly News for “several days.”

Those who were betting Williams would ixnay the ookingbay insisted the optics would be awful ducking Nightly News while going on a late-night comedy show, as his division struggles to clean up the brand damage he’s created.

Others, however, had argued Williams has got to start doing the Career Salvation Stations of the Cross Tour somewhere soon, especially if he intends to hang on to his gig as Nightly News anchorand managing editor of the division.Letterman, they argued, has senior statesman status, as TV on-air talent goes. He and Williams go way back, they noted. Plus, Letterman’s show was one of the places were Williams made his bogus claim about having been on the helicopter that took the RPG attack. Video of that 2013 appearancehas been making the rounds since Stars and Stripes published its report.

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An apology to Letterman on his show would actually look good, said enthusiasts of the now-aborted booking. Letterman, they’d insisted, would be the perfect person to hold Williams’ hand as he does a TV mea culpa — having himself demonstrated in 2009 how to make Late Show a platform for a confession, using the studio audience’s applause and laughter to begin the process of public forgiveness.