This discussion is getting caught up on things that don't have any direct bearing on this case. The case is about equal protection under the law.
Forget who was careless and who lied to whom. Water under the bridge. As usual, the question we need to deal with is, "What now?"
I think this is a solid case, although I'm not holding out hope that judges (who are typically socially conservative) will agree with me.
As it stands now, the woman is given the opportunity to sever her legal responsibility for the resulting pregnancy through abortion or adoption. She is given this opportunity regardless of whether she was careless, unlucky, or a victim of dishonesty. This decision is unilateral, and does not depend on biology: adoption, at least, is a strictly legal entity.
Given that, why should the man be denied that same opportunity? Why does the woman have the right to wash her hands of the entire affair if she desires, but the man doesn't?
This isn't about sympathy, whether people acted stupidly, or whether they should accept responsibility for their actions. Those are all good things to discuss, but they have no bearing here. The only thing that matters is whether it's equitable for one sex to have legal power that the other doesn't, pure and simple.