It is not Mormons who are being pillaged but Mormonism. Like most critics of Mormonism, I have several Mormon friends and I would not allow anyone to personally attack them. Their religious beliefs, like mine, are open to criticism.
As their religious beliefs affect you, feel free criticize, but as to the beliefs themselves, who cares? It is just a weak indirect attack on Romney who has enough real liberal baggage to swing at. It invites scrutiny into everyone religion which is inappropriate and irrelevant.