Because given a choice between a moderately sane (for a Republican) daughter of the last Republican presidential nominee and the certifiable nutcase whose contributions to the public discourse include calling John Edwards a faggot and suggesting that we should kill all the men in the Middle East and convert all the women and children to Christianity, RedState goes all in with the psycho.
The best thing about RedState's problem with Meghan McCain? Their dislike has nothing to do with her positions on anything, or even her dislike for Ann Coulter. No, they're pissed because she couldn't bring herself to vote for the guy whose campaign slurred her father and mother using some pretty odious racial push polls, and whose supporters suggested that her father had been brainwashed while he was a goddamn POW undergoing torture in Vietnam. If all Meghan McCain did was not vote for George W. Bush, then she held herself back pretty well, I'd say.
So you go ahead with your bad selves, RedState. The more you target the moderates in your party and side with the loonies, the longer my side will have to clean up the mess you left us.