Rush Limbaugh on Family Guy

This is old news, but I watched the Star Wars episode of Family Guy recently and saw Rush Limbaugh's name in the credits. Here is the scene he was in. Its pretty funny. When I first saw it, I thought they did a really good impression, apparently it was really him. The weird thing is, this is about the only cameo he's ever done. The rest of his IMDB page is just News and NFL shows. I wonder how he ended up being on Family Guy. It is definitely not a conservative show.