"What you have in a polygamy case is a situation where you're going to have multiple partners, and there is all sorts of evidence that that has harmful effects on some of the people participating and on the children."
Heh.
Now, I could also turn the homosexual agenda's talking points on him here:
Polygamy is practiced among mammals all the time. It's natural, so it must be normal.
Polygamy is attested among humans for millennia. Even Biblical patriarchs practiced polygamy and took maidservants as their own wives.
Many humans are simply not meant to be monogamous and settle with just one partner. Half of all marriages have some sort of adultery going on. The only reason this causes mental strife is because society stigmatizes it with bigoted terms like "adultery." The way to end this stigma is to normalize it, and that starts by allowing the courts to recognize the right of more than two partners to marry into one union. Why, if a man loves more than one woman (or man, for that matter), should he be bound arbitrarily by the two-person limit to a marriage?