I think the key to understanding O'Reilly's admittedly poor understanding of the tea party movement stems from his days as an investigative journalist:
The journalistic ideal, of course, is "neutral point-of-view." Such an ideal is a near impossibility in anything except encyclopedic writing, but it is the ideal that journalists the world over now aspire to.
Bill O'Reilly isn't a journalist. As the video above shows, he was a journalist as recently as 1995, shortly before Fox News came on the scene.
Most Americans are not ideologues. They are just folks who want a fair system and a noble country.
Spoken like a true journalist, and true even as far as it goes, but it kind of misses the point. When you hold a neutral point-of-view as your highest possible journalistic achievement, then anyone with a strong opinion becomes an ideologue.
I truly believe that O'Reilly fancies himself a journalist, when in truth, he was hired by Fox News Channel as a pundit. Pundits ought to ground their opinion in truth and in fact, but pundits don't have to maintain that neutral point-of-view. I think it tends to be destructive to the conservative movement as a whole, and the tea party movement in particular, when pundits (and that means you, Bill O'Reilly) try to be something they are not.
Get over the self-loathing, Bill. The left will call you an ideologue whether you claim to be one or not. Might as well embrace it.