My experience among HN, and nerds in general is that it is common to find people who like to take a 'neutral' stance in a debate, verging on being the devil's advocate, and trying to find the good on both sides.

I think it comes both from a love of rhetoric and from a point of view that being a contrarian can make you appear smarter, or more interesting.

I know I've been guilty of such behavior.

I did not follow the Roe vs Wade thread specifically, so my view may be out of touch, but from what you describe it seems to be closer to this kind of behavior rather than actual conservatism