If a prominent conservative radio personality chooses not to use his influence to promote his ideology in time he will become irrelevant. We tune in to be inspired not just entertained.
Did he really have to say "don't vote for McCain" when that battle was over? Not to his audience.
I'm not saying I don't wish that he would come out a little stronger in this election. But I can certainly understand his decision and respect it. He has done his part.
Personally, I'd rather he ran. Worst case, he gets hammered over the vicodin. Best case, he takes it head on, gets past it, and gets nominated. Who doesn't think Rush can't take on the MSM the way Reagan did? He's one of the last vestiges of Reaganism left. We are back to 1975, folks. The GOP is a party of moderates saying "me too" and following the Dems into socialism and social libertine behavior. Back then, there were a few writers (Bill Buckley most prominently) a very few academics, and almost no politicians who you would call conservative in the Reagan sense of principled philosophical conservatism. Reagan created it, and remade the GOP into a conservative party. The Bushes and their people then spent the last 19 years destroying what he created, and the job is almost done.
That's why the outcry for a Reagan. Conservatives are sensing that we need someone to retake the party, or it will be back to the tired old Rockefeller/Romney/Ford party of the 1970s. Rudy and Mitt fit right in with that party. Thompson would have been on the fringes, but he could have gotten along. Duncan Hunter would have been an outcast to them, a neanderthal with wild ideas who made them look bad to the Washington Post. Reagan gave us Hunter as mainstream GOP (in fact, they came in together as I recall.) Bush I and II have, in the words of Peggy Noonan, squandered all of that. Intentionally, I think.