O'Reilly is not an ally, he is a P. T. Barnum.
He strategically charts out extreme positions that are all over the map.
That way, sometimes one of his positions matches yours, and you say "I like this guy!"
Two minutes later he takes a polar opposite position on another issue, but it takes a long time to notice the pattern.
O'Reilly is a ratings whore, period.
Jenna Jameson told a story once about appearing on his show where he bashed her and trashed her for being a porn star who contributed to the moral decay of society. After her segment, he complimented her, and told her he was a big fan and enjoyed her work, and asked her to send him all her latest videos. Typical.
I think you're on to something. I you think about it, quite a few use this formula, including Dick Morris and Pat Buchanan. If you listen long enough you can figure our their real political bent, and it ain't conservative. I just don't have the time or motivation to listen to most of them long enough to figure it out, so I'm becoming very cynical of all of them.
It's all about selling advertising.