Turning on the radio is not the same as voting.
The thing is, Rush hasn't even been criticized for it. There was a thread the other day about Rush dating Daryn Kagan, and most posters had no problem with his multiple marriages, let alone dating a liberal so rabid she almost cried on-air after Algore lost in 2000.
While questions of leadership could be raised, given the divorce rate right now, I don't think the voters would care. And Rush would still have 22 million listeners.