The fact that he hasn't shows you that the Dims no longer see talk radio as a threat. That's why they've changed tactics and are using corporate ad warfare against Breitbart and Tucker Carlson, and lawfare against Newsmax, Trump, Flynn, and others. All while passing laws to give government money to press institutions that toe the Dim party line.
I agree I think what they are really doing is to kill off the revenue stream so the can sell off the AM spectrum to their cell companies buddies and get a bunch campaign cash in return.