I think Digby goes a little far here. Confused polling on abortion is evidence that Americans have confused views on abortion, not that the cover story obscuring their Handmaid's Tale instincts is insufficiently clever. So while the Mysterious D offers as convincing a logical condemnation of a conflicting position as one could hope for, I'm not sure that's quite the right lens to use.
Now, I'm about as anxious to enter the abortion debate as Tom Cruise's agent is to talk about Thetans, but it seems to me that the whole method we use to understand the conflict is flawed. Efforts to conceptualize the conflicting positions tend to push supporters onto a binary choice: either you do believe the fetus is a life (0), or you don't (1). From there, Digby's point makes perfect sense. Murder is wrong, even when the life is caused by rape or incest, so if you profess to be a 0 but support exceptions for assault or familial relations, you're probably a liar, and your real agenda is probably rather ugly. True that.
But my guess is that most folks (though obviously not all) fall midway on that scale -- .2's, .4's, .6's and so forth. The fetus, to them, is a quasihuman, analogous to dogs or cats. Either animal, when kept as a pet, gets anthropomorphized to a rather absurd degree, attaining rights we don't grant to other animals but not quite reaching the human degree. Thus we enact animal cruelty laws but allow euthanasia in case of abandonment. We believe the animal shouldn't be hurt, but if no one gives it a home, society is happy to kill it. It's a rather confused view of the subject, both legislating to protect the creature's life and rights but allowing its murder when humans won't facilitate its existence. But if the thinking is almost criminally muddled, it's not really disingenuous. Society values the life, but not too much. And that, I think, is a pretty good map to the abortion debate as it plays out among those not deeply involved in the discussion. Wrong and confused, but not in a premeditated fashion.