Or is that because polyandry ought to be measured against polygamy rather than polygyny?

No, wordcrazy got it right. Polygamy is a general term, referring to a marriage that includes more than two people. Polygyny and Polyandry are specific terms-- polygyny is one man married to two or more women, polyandry is one woman married to two or more men.

If you already knew this and were trying to make a humorous point, which I failed to pick up on, forgive me for being pedantic!
But I have to show off my Anthropology knowledge somehow...