Not petty -- he's essentially correct in his analysis. Conservative talk radio doesn't disseminate "conservative thought." In it's current form it is little more than a mouthpiece for a few guys' personal opinions, presented in a manner designed to entertain and tweak the emotions of its niche (large, but niche) audience.
It depends on which show you're listening to. Savage doesn't. Hannity is entertaining but, shall we say, a little shallow on the philosophical front.
But, then, there are Limbaugh and Levine and a group of local hosts -- Mark Davis (DFW), Mark Belling (Milwaukee), Jason Lewis (Twin Cities), Hitchcock (San Diego), along with Mark Steyn, etc. -- who have a large philosophical and intellectual component to their shows.
It's no coincidence that the local list also constitutes Limbaugh's "bench".
The primary attraction and entertainment value of talk radio, to me, is that it makes me think!