Gary D. Gilbert is one other such example. On-air he was right-wing shock jock “Gary Dee” over Cleveland radio in the 1970s, but in private was fairly mild-mannered … most of the time. Unfortunately his on-air persona famously took over him several times and he was arrested on charges of abusing his wife, TV personality Liz Richards. His comeback attempt in the late 1980s not only fared poorly, it helped initiate hearings on indecency by the FCC.Hate to tell you, Patrick...
Having worked for many years with a bunch of people who worked with Rush, and having some mutual friends (all told, about 20 people), Rush was, at least until 2010 or so, much more moderate than his on-air persona.
It's possible that he evolved to a more hardline set of beliefs in the final 10 years of his life and career, but as people above noted, in talk radio, every day you need to stir the pot. And it's even more critical when you align yourself with a political movement that doesn't take dissent or contradictory facts well.
Basically, in that situation, you're the guy feeding the alligators. If you run out of red meat, they'll eat you.
I would tend to believe that, up until 2009, Rush the person and Rush the on-air talent were two (mostly) different people. What followed in the decade afterward is reminiscent of what happened to cartoonist Al Capp; in his last decade drawing Lil’ Abner, the strip sharply changed in focus and became painfully political and a vehicle for Al’s worldview, which hardened with the political turmoil of the late 1960s.
Had Rush retired in, say, 2008, he probably would be reflected on differently. Maybe not a lot differently, but differently nonetheless.