Paul is absolutely NOT a constitutionalist, he is the most dangerous type of statist imaginable.
Neither the term nor concept of "states' rights" exists ANYWHERE in the Constitution.
We the people have rights which come from God and are unalienable, to protect these rights We the people grant "powers" to the federal and state governments. However, governments are never given the power to infringe upon our individual rights, in fact it is expressly forbidden.
Unfortunately, Ron Paul and his followers have a blind devotion to the falsehood of "states' rights" and to this end they endeavor to bestow upon the individual states the power to trample God-given individual rights.
God given rights are all individual, so they belong to the people and not to the states.
A “state” does not have a RTKBA...an individual does.
A “state” does not have a right to life...an individual does.
A “state” does not have a right to free speech....an individual does.
Perhaps you are unfamiliar with the 10th amendment?
The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.