I'm late to this show...but your question was excellent. Why not use the argument that abortion should be opposed because it goes our instinct of self preservation, the other side does not create policy from the result of logical deduction OR from what a sane person would consider moral. In politics...you want to WIN;...creating policy in a constitutional republic or a democracy or whatever the hell we are now, you have to incrementally change policy as your side wins. Using every possible arguement to "speak" to the largest crowd willing to listen makes sense to achieve polical and moral goals of conservatism.
In my opinion, that's the point. You must use every possible argument that you can. You simply must.