Christian Siriano has a rule: he doesn’t dress Real Housewives. If he loaned to every one of them, he says, there’d be nothing left to send an Oscar winner like Nicole Kidman. Siriano says he made the no-Housewives rule years ago, back when the franchise was exploding and the cast members kept asking to borrow clothes. His line: “I can’t be, like, your closet.” Nicole Kidman steps out at the Practical Magic 2 premiere held at Directors Village i…