Politico
by Dylan Byers
December 26, 2012

NBC's David Gregory, the subject of a now-popular police investigation, is on vacation and will not host this Sunday's edition of "Meet The Press."

"David has long planned to be off on Sunday, Dec. 30th. He will return the following Sunday," NBC News spokesperson Erika Masonhall told POLITICO.

The Washington Metropolitan Police Department launched an investigation this week into whether Gregory and NBC violated city laws when he displayed what appeared to be a gun magazine on last week's show.

(excerpted)
http://www.politico.com/blogs/media/2012...the-152814.html

Yes, Gregory displayed a 30 round magazine for an AR-15/M-16, in violation of Washington DC law.

DC, as you know, falls under the jurisdiction of the Federal Court systems for this type of crime.
He won't be on MTP because the DC police would be able to arrest him on set for violation of the law.