I agree. The invasion of the US is not a "social issue". It's a matter of citizenship and following the law. It's not a social issue to say EVerify should be the law of the land and people in the US illegally should be sent home.
The social issues, along with a whole lot of other issues, should be issues for the states to decide. If Rand Paul presented this as such, I suspect he'd get across-the-spectrum support.
If you listen to Paul and the other pro-invasion candidates, the illegal infestation is a social issue.