rock in this sentence means that the broadcast will be awesome...

I feel as if a large chunk of the sentence is missing, because they could be interviewing 'the rock' or the interview will be awesome, either way it's poorly phrased

'Rock' in this sentence can mean effective as well as enjoyable (or pleasing). Rock means the interview will be great and viewers will love it. After working very hard preparing for a test, one can say, I will rock the test today. Also, the 'an' in your sentence should be 'the'.