Shouldn't the State's Rights advocates be all up in here defending SC's right to do awkward stuff like this?
I don't know what the State's compelling interest in banning truck nuts might be, but I don't know that truck nuts really impart information or ideas in ways commonly defined for freedom of expression. I'm for leaving well enough alone, but I'm generally for fewer laws rather than more, and I'm certainly not the litmus test.
Obscenity laws are among the most bizarre in the United States, though - hell, let's start with the notion of "community standards" as a test and just quit on it for good. I wouldn't touch them with a 10-foot pole (that has a glans and balls attached, of course).