Whole Foods CEO John Mackey is on a whirlwind nationwide book tour.

This week, he’s in Washington, D.C.

Yesterday at the Cato Institute.

Tonight at the National Press Club.

Signing his book — Conscious Capitalism (Harvard Business Review Press, 2013) at a Whole Foods store in DC.

But between all of that, Mackey was scheduled to be on National Public Radio’s Diane Rehm Show for an hour.

But then, all of a sudden, his appearance was cancelled.

Why?

Diane Rehm Show producer Rebecca Kaufman confirms that Mackey’s appearance was scheduled and then cancelled, but she won’t say why it was cancelled.

“I’ll have Diane get back to you after she gets off the air,” Kaufman says.

No such luck.

Mackey’s handlers at Whole Foods did not return calls seeking answers.

Last month, Mackey, a committed libertarian, used the word “fascism” to describe Obamacare.

“In fascism, the government doesn’t own the means of production, but they do control it,” Mackey told NPR’s Steve Inskeep. “And that’s what’s happening with the health care program with these reforms. So I’d say the system’s becoming more fascist.”

Mackey backed off within 24 hours, telling CBS the next morning —  “Well, I think that was a bad choice of words on my part. I regret that. Yes.”

And later in the day telling WNYC — “I realize that that word has so much baggage associated with it, from World War II with Germany and Italy and Spain, that that’s just such a very provocative word so I regret using it.”