I can't really find anything ever written in that era that said that federal laws supercede state laws.
The supremacy clause is what makes the Mississippi Legislature's ("40 hissing possums in a barn" - Jon Stewart) so amusing.
First of all, Mississippi has no PA law, and the fed govt has not passed a PA law saying restaurants or bakers have to serve gays. SOOOOOO, even before our "new" law, nobody had to serve gays. That is, the law accomplishes nothing, beyond letting the possums vote to say they agree with not serving gays.
Secondly,. the act provides:
"3) The purposes of this section are as follows:
(a) To restore the compelling interest test as set forth in
Sherbert v. Verner,374 U.S. 398 (1963), and
Wisconsin v. Yoder, 406 U.S. 205 (1972), and to guarantee its application in all cases where free exercise of religion is substantially burdened; and....
Basically, the congress and the scotus got into it over whether a law that on it's face does not discriminate against any religion may nevertheless run afoul of the First Amend if it impacts a religion - in that case it was whether Native Americans could use peyote in religious ceremonies. The Scotus said NAY, and the congress passed the Restoration of Religious Freedoms Act. The scotus has thus far declined to say Yay or Nay to the RRFA.
But this Act accomplishes nothing. If the scotus overturns the federal RRFA, this law cannot protect any individual from the application of federal law. That is, Mississippi native americans get no peyote ... of course they don't want any .... But god dammit the Hissing Possums must SPEAK