Suddenly
No Punting
I don't know.
But I don't think it comes down to integrity at all, but political strategizing.
For example, "states's rights" makes sense to a party that wants to pander to the evangelicals of the south, but also the more urbane (talking relatively, here) northerners.
If they pick up votes by banning abortions and gay marriage in the south, but allowing both in, say, northern states and Florida, then surely they are more likely to do that.
"States rights" has always been a neo-Confederate buzzword that only means they don't want the federal government interfering with the state's ability to be as repressive as it wants. It wasn't like the south was out there protesting the fugitive slave act or anything.
A nationwide abortion ban would be on brand. It is probably inevitable because the GOP is going to need a way to keep using abortion to rile up the base and that's the obvious way to do it.
I mean, it would be hard to find Constitutional justification for such a ban as they'd need to connect it to interstate commerce, but I doubt the conservatives will still be concerned about the commerce clause being too broad.