Security guards are not that unique. Didn't Jerry Springer used to have them all the time, when they had couples like the ones in the cast talking about who cheated on whom and there would be fights sometimes?
But Jersey Shore probably got MTV and BM to drop the zero-tolerance for fighting rule, because of the boffo ratings that JS got at first.
So hiring guards to keep things from getting completely out of hand was probably a minor expense.
Look how famous and rich Snookie got throwing bottles at that doofus in the cast.