There's a reason for that.
Liberal Progressives* -- including liberal-progressive Republicans -- want to stretch the definition of "conservative" to the point that it's broken. And they want to make "Republican" fully substitutable with "Conservative." Controlling the terms of the debate in this way gives them an advantage in the war of rhetoric and makes it easy to stigmatize and bastardize conservatism.
The faux outrage over exclusion of liberal-progressive Republicans from conservative gatherings is a fine example of the liberal impulse to define conservatism for conservatives, as Ace aptly points out:
The gathering is called C-PAC, not R-PAC. Chris Christie's success as a registered Republican does not qualify him automatically as a "certified" conservative. I hate the Conservative Purity Purges as much as the next person.... but in this case? I think there is a valid point to be made.
Chris Christie is not just soft on the Second Amendment. He is downright hostile...
Politicians who don't trust law-abiding citizens to own guns do NOT see them as equal members of a democratic republic. To put it bluntly, they see them as serfs...Read the rest.
*I don't want anybody to feel left out.