Prop 8 says, "one man one woman" so clearly that means one man, two woman is illegal as is two men or two women.<quoted text>
That you argue so vehemently that prop 8 didn't also ban polygamy tells us all we need to know about your motives.
I really don't see the point otherwise.
Our resident authoritarians might as well argue that 1+1 doesn't equal 2.
Perhaps they have no motives and just like Christians are told by their mommies that there is a God, perhaps the mommies of authoritarians told them polygamy is wrong and now they will insist on it for the rest of their lives because no new information will get in to show them how wrong their mommy was about this.