This sounds a lot more complicated than just Stern being taken off the air. He could sue, but if the government is forcing even Infinity to take him off the air, fighting them may be futile. Even Stern says if Infinity is fined now, there's no way they can fight back.
Listening to Howard this morning, things sound dire. It may be Stern is blowing things up worse than they are, but considering some of the things he said (Tom sending tapes of the show to investigators, Mel Karmazin being persuaded to take Stern off the air), it's unlikely.
It seems like a lot of people don't care, unfortunately.