My understanding of the use of "mindkilled" is that people who can be so described are incapable of discussing the relevant issue dispassionately, acquiring an us-vs-them tribal mentality and seeing arguments just as soldiers for their side. I really don't think that this applies to the topic of abortion on LW, which can be discussed dispassionately (much more so than in other places, at least). This is quite compatible with the possibility that the LW consensus is biased and wrong, which is what you are suggesting.
For example, what would be inappropriately off topic to post to LessWrong discussion about?
I couldn't find an answer in the FAQ. (Perhaps it'd be worth adding one.) The closest I could find was this:
However "rationality" can be interpreted broadly enough that rational discussion of anything would count, and my experience reading LW is compatible with this interpretation being applied by posters. Indeed my experience seems to suggest that practically everything is on topic; political discussion of certain sorts is frowned upon, but not due to being off topic. People often post about things far removed from the topics of interest. And some of these topics are very broad: it seems that a lot of material about self-improvement is acceptable, for instance.