The problem we are seeing with Rush, isn't just Rush himself, but a changing society. I do believe in his core, Rush is a Conservative, but like many, they become either so jaded or so caught up in 'the game' that winning or playing the game has superseded their values.
When I was young (yea, I was a little Alex P Keaton). Conservatives actually read William F Buckley and watched Firing Line. They studied Goldwater and Rothbard. They could actually tell you in detail the difference in the Chicago School, Austrian School, and Keynesan Economics. These days, if you take any self-proclaimed Conservative activist off the street, many would have no clue what they were or how they work. (they probably would think the Chicago School of Economics was some communist plot).
Now, Conservatives, just like the rest of society, are addicted to clickbait and drama. They want flashy headlines and easy answers. They want leaders to appeal to their emotions and get them waiving flags. They don't want to debate and discuss with their opponents, they want to hate them. They want to scream at the TV and internet. They don't want to refine their arguments or study. They have traded Firing Line for Duck Dynasty. They have traded National Review for Free Republic.
The changes with Rush are very much a symptom of this greater change. He is just appealing to what he thinks his audience wants.
He thinks (and probably rightly so) that they don't want "Advanced Conservative Studies" any more. They want a sports announcer pitching WWE catch phrases and calling their opponents names. They want someone who paints the boogey man in a dark light and paints their hero as someone who can do no wrong. They don't want someone who discusses the 'why' or 'how', they want to just hear the 'who' so they know what team to root for and against.
Rush's change is society's change and we can only look in the mirror to see why.