In this article about Mormon women seeking priesthood ordination (strictly speaking, though, what they really want is priesthood conferral), church spokesman Michael Purdy gives as justification for the church's male-only priesthood, "The Church follows the pattern set by the Savior when it comes to priesthood ordination." Meaning that the biblical record and ancient mainstream Christian tradition has no record of Christ conferring the priesthood upon women or ordaining women to priesthood offices.
Of course, we know that the biblical record is scant at best. The Bible itself says as much. Saying "well, the Bible doesn't mention it" is far from iron-clad reasoning.
Combined with the new introduction to Official Declaration 2, I would not be philosophically troubled by a future declaration of female priesthood conferral, though I think these groups should have more of an attitude of petition and less of demanding.