By whom?
By the mainstream media. Yeah, yeah, I know. What do we care? The media has been flailing at Rush for a decade and a half, and what has it gotten them?
This time they have an issue that has bite to it. They'll portray this a a typical bigwig moneybags hypocrite caught in the same kind of conduct he has railed against in the past. Hey, they'll think, it worked against Newt Gingrich, right? Prepare for the onslaught. Every mention of Rush in the mainsteam media will be prefaced or appended with a reference to his stay in rehab or his addiction to strong painkillers. Every comment he makes about a rat candidate will be brushed aside with some joking comment along the lines of "Why doesn't Rush just stick to what he knows best and talk about illegally obtained drugs?"
This is going to ding his credibility. To think that it won't is probably not realistic.