They also had success in Michigan, Alabama and Mississippi. Any open primary is vulnerable to their prank voting effort.
Are you sure they're not Dems who are social conservatives? Until things "settled down" after Roe v. Wade, Democrat pols were more likely to be social conservatives than Republicans were. Lord knows, GOPe still has no use for social conservatives. There are lots of Dems who are socially conservative (I wouldn't hazard a guess as to numbers) who remain Dems -- partly because of historical reasons (like family tradition) and partly because the GOPe doesn't offer an attractive alternative.