Now that you've speculated, here's why (an excerpt from the NYT story):

For Bob Costas, the issue was not complicated.

The longtime NBC sports and talk show host, who signed on this year to be an occasional substitute for Larry King on CNN, resisted a request last Thursday to be the host of a King program devoted to interviewing guests about the already widely covered Natalee Holloway missing-person case in Aruba.

When he could not get the show's topic changed, Mr. Costas said he respectfully decided not to participate.

"I don't believe there was a single American who was sitting around saying 'I'd really like to see Bob Costas's take on this,' " Mr. Costas said in telephone interview.

Having a host oppose a topic and decline to participate in a show is certainly not common, though hosts of morning shows like "Today" have been know to refuse to interview certain guests. But Mr. Costas is not an employee of CNN and has wide latitude about deciding if he will take part in a program.

Mr. Costas said he had found out "about two days before" the show that the topic would be Ms. Holloway, who disappeared on May 30. He told the producers that he hoped the topic would change. On Wednesday, when he learned that it would not, he declined to serve as host. The program went on with Chris Pixley as the host.

"Nothing had been spelled out about my being able to turn down certain topics, but it was implied," Mr. Costas said. Jonathan Klein, president of CNN's domestic operations, backed that up, saying, "It's important that we never have an anchor doing a story he does not believe in."

Mr. Costas's decision has drawn further attention to the Holloway case, which has become the latest in a stream of stories about missing young women that have been turned into daily - if not hourly - staples of coverage on all-news channels.

Many critics have questioned why the story of the disappearance deserves blanket coverage. Some have deplored the emphasis on white women who go missing, while missing women of other ethnic groups are ignored. One critic, Matthew Felling of the Center for Media and Public Affairs, told The Associated Press that the Holloway coverage amounted to "emotional pornography."

Now that I've read the post more thoroughly, I would amend my headline to say Bob Costas is an admirable guy.

This was not a story he wanted to cover, and so he said no.

For a related story, check out this post at Canadian Journalist entitled Missing in the media: anyone NOT young, white, pretty and female.