When he's under oath. His radio show is not a deposition, grand jury or witness stand.
I don't understand your point. You seem to believe he should provide evidence that can be used against him in his radio show so that he can claim the 5th during trial. That makes no sense to me.
I don't expect him to incriminate himself on this show. I don't hold that against him. I am disappointed in his conduct and any money he (allegedly) may have contributed to the illegal drug trade, albeit prescription. Nonetheless, as long as he does not lie publicy, I'm content for him to remain silent and take care of his problem. Law enforcement and prosecutors will determine if there is a need to charge him. It's not like he is a violent perp. He has only damaged himself and betrayed the trust others had in him. He is still an articulate spokesman for what millions believe, albeit his role will undoubtably be diminished or changed.