Seriously? OMG! WTF?

Miley Cyrus was on Today today and she was goofing around for the cameras. The Voice coach didn’t know her mic was hot, so she said, “There’s no sound, so it doesn’t matter what I saying. Right?” Then she looked at the camera and yelled, “F*ck,” and then everyone in the control room said it.
Didn’t they know to have her on a 7-second delay? I thought that was a given on live TV.