We can't licence polygamy without also promoting polyamory. Traditional polygamy, by its nature, will have limited appeal in America (as Tierney correctly notes). But (which Tierney ignores). Take away the stigma against multiple-partner marriage, and our larger family system will be profoundly weakened. It's the stigma and the resulting secrecy
that limit the social effects of multi-partner unions now. Change that, and you will see deep systemic consequences.
Consider what motivates someone to write "polyamory has much greater potential appeal, and poses a much deeper danger to the American family." I have no idea if "polyamory has much greater potential appeal" or, if it does, why it "poses a much deeper danger to the American family" than does polygamy.
I'm glad I don't live in Kurtz's brain.